Metering In Today’s World KEEP IT SIMPLE By Larry Chapman 1
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Blondel’s Theorem • Blondel’s Theorem—In a system of N conductors, N-l meter elements, properly connected, will measure the power or energy taken. The connection must be such that all voltage coils have a common tie to the conductor in which there is no current coil. 4
Blondel is right, Everybody Else is WRONG! • When metering applications agree with this simple guideline there will never be an error or compromise in metering accuracy and we would be living with 6 meter form numbers and 6 basic wiring schemes. • Metering, in general would be understandable, straight forward and easily mastered. • We can thank our lucky stars for the nature of engineers in general, because without them trying to prove ways to get the job done without following Blondel’s plan this course would be very short. • So, lets get down to learning how to play the hand we have been dealt. 5
Definitions of Abbreviations Common to Metering • • Kh: Watthour constant of the meter. Equal to watts per single disc revolution. Solid state meters will have an indicator of some fashion for this value. Rr: Register Ratio, normally indicated on the face plate or stamped in the body of the register. Rs: Ratio of the first driven gear on the register to the meter disc shaft. Not indicated on the meter in any way. Value must be determined. CTr: Current transformer ratio. Never accept nameplate information. ALWAYS verify. Always depicted as some value to 5 for the maximum secondary current. VTr. Voltage, or Potential transformer ratio. Never accept nameplate information. ALWAYS verify. Usually depicted as some value to 120 for the maximum secondary voltage. TF: Transformer Factor. (CTr/Turns)XVTr=TF. Turns equals the number of times the primary current is presented to the current transformer. NEVER assume this value to be the billing multiplier! PKh: Watts per single disc revolution with the transformer factor applied to the meter Kh. Kr: Register constant, better known as the billing multiplier. ALWAYS run the billing multiplier formula to verify this value. 6
Common Metering Formulas • • R. G. : Register Gear Ratio. Derived by 10000 / Kh = R. G. IE: 10000 / 7. 2 = 1388 8/9 • • Rr: Register Ratio. Derived by R. G. / Rs = Rr IE: 1388 8/9 / 100 = 13 8/9 • TF: Transformer Factor. (CTr / Turns) X Vtr =TF Consider a service with a single 400/5 current transformer and two primary turns at the CT and a 480/120 VT. IE: (80 / 2)X 4 = 160 • • • PKh: Primary Kh. Meter Kh X TF. A value utilized to calculate load or register ratios to compensate for the transformer factor. IE: (0. 6 X 160) = 96 7
The Two Most Important Formulas Ever • Kr: Billing Multiplier (Rr X Rs X TF X Kh) / 10000 • This is absolutely the most important formula you will ever learn for dealing with electromechanical meters! • When solid state meters become involved the recommended procedure is to apply the transformer factor as the billing multiplier and program the meter with a Kh equal to that indicated on the nameplate. NEVER use primary rated register programming, it only sets you up for disaster. KW: Determined by a timed disc revolution at the meter. • (3. 6 X Kh. X TF) / Time in Seconds for 1 Disc Rev. = KW • IE: 3. 6 X. 3 X 160) / 28 Seconds = 6. 171 KW • • NOTE *** 3. 6 = the number of seconds in one hour / 1000 8
Other Formulas of Interest • VA: Volt-Amperes. Volt X Amps = VA IE: 120 X 10 = 1200 VA • Watts: Volts X Amps X Cosine of the Phase Angle = Watts IE: 120 X 10 X Cos 30 = 1039 Watts Since our product is sold in units of 1000 and billed to our customers as Kilowatts or, in some instances, Kilovolt Amperes we simply convert VA and Watts as follows. KVA: VA / 1000 IE: 1200 / 1000 = 1. 2 KVA • • • KW: Watts / 1000 IE: 1039 / 1000 = 1. 039 KW KW must be viewed as demand not confused with KWH is simply the sum of the KW consumed over the period of 1 hour. This is the value displayed on the meter register. The demand is determined in intervals of time and calculated to indicate what that consumption would be if the load remained constant for a full 60 minutes. 9
Other Formulas (Cont’d) As meter people we are not at all interested in having to deal with gathering the information required to prove the accuracy of the metering package from any place other than the meter socket. For that reason, the rest of these formulas are based on that assumption. There as many formulas to calculate these values as there are engineers to dream them up, and you may be more accustomed to using others to get the same answers. • Calculating KVA • Single Phase 2 -Wire Circuit: • (Line to Line Volts X Total Amps X TF) / 1000 = KVA • IE: (120 X 5 X 160) / 1000 = 96 KVA • Single Phase 3 -Wire Circuit: • (Line to Line Volts X Total Amps X TF) /2000 = KVA • IE: (240 X 160) / 2000 = 192 10
Other Formulas (Cont’d) • Polyphase Circuit: • (Average Line to Line Volts X Total Amps X TF) / 1732. 05 = KVA • IE: (208 X 15 X 160) / 1732. 05 = 288. 21 • **** NOTE **** 1732. 05 is derived from the Square Root of 3 X 1000 • In the event readings are taken at a 3 -Phase, 3 Wire socket and the current for the 3 rd phase is not available, simply add a value equal to the average of the other two to the total current. • If a form 5 S or 45 S meter is being used with a 3 Phase, 4 -Wire Delta circuit with two current transformers, enter the reading of the single phase current transformer twice to the formula to compensate for the double primary adjustment in the transformer factor. 11
Other Formulas (Cont’d) • Polyphase 3 -Phase, 4 -Wire WYE Circuit with 5 S or 45 S Meter Scheme: • ((Average Line to Line Volts X Total Amps X TF) / 1732. 05)*Cos 30 = KVA • • IE: ((208 X 17. 3 X 160) / 1732. 05)*. 866 = 288. 21 **** NOTE **** 1732. 05 is derived from the 3 X 1000 • In this instance the center phase current is presented to the CT on the left meter element backwards and again to the CT on the right meter element backwards. The Cos 30 value of. 866 compensates the formula to allow for this discrepancy. Next we look to calculating power factor using two electromechanical meters to collect KWH and KVARH information, or reactive load, information. There are two accepted methods of determining KVAR. 12
KVAR, KQ, KVA, Who Cares? • • The formula for using meter revolutions disc is the same for KW, KVAR, and KQ meters. (3. 6 X Kh. X TF) / Time = KW, KVAR, or KQ IE: (3. 6 X 1. 8 X 160)/10. 368 = 100 KW. If the Watt and Var meters are running the same speed KVA is derived from the formula: KVA = (KW₂ + KVAR₂ ) IE: (100₂ + 100₂) = 142. 421 KVA Power Factor = (KW / KVA) IE: (100 / 142. 421) =. 7021 or 70. 21% As long as the two meters involved are simply a KW meter and a KVAR meter the above holds true and all is well. Once we take on the “KQ” meter everything changes. 13
The “Q” Meter • • • With a “Q” Meter in the equation we first have to determine the value of KVAR using: (3. 6 X Kh. X TF) / Time = KW, KVAR, or KQ IE: (3. 6 X 1. 8 X 160)/10. 368 = 100 KW. If the Watt and Q meters are running the same speed KVAR is derived from the formula: KVAR = ((2 X KQ)-KW) / 1. 73205 or the 3 IE: ((2 X 100)-100) / 1. 73205 = 57. 735 KVAR KVA = (KW₂ + KVAR₂ ) IE: (100₂ + 57. 735₂) = 115. 47 KVA Power Factor = (KW / KVA) IE: (100 / 115. 47) =. 866 or 86. 60% If your customer is trying to correct his power factor though addition of capacitance it is clear that using the wrong formula for your calculations would certainly create confusion. 14
Metering Formula’s Simplified • Transformer Factor: (CTr X VTr) / Turns Primary at CT = TF IE: (40 X 2. 5) / 1 = 100 • Multiplier: (Rr X Rs X Kh X TF) / 10, 000 = Kr or Billing Multiplier IE: (111. 1111 X 50 X 1. 8 X 100) / 10, 000 = 100 • Primary Kh: TF X Kh = Primary Kh IE: 100 X 1. 8 = 180 • KW by Timed Disc 3. 6 X Kh X TF Time, 1 -Rev in Seconds Meter Socket KVA Formula’s 1 -Phase 2 -Wire Svc: (Amps X Volts X TF) / 1000 = KVA 1 -Phase 3 -Wire Svc: ((Amps “A” + Amps “B”) X (Line to Line Volts) X TF) / 2000 = KVA • 3 -Phase 3 -Wire Svc: ((Sum Amps “A”, ”B” and “C”) X (Line to Line Volts) X TF) / 1732. 05 = KVA **** Amps “B” is the average value of “A” and “C” **** • 3 -Phase 4 -Wire Svc: ((Sum Amps “A”, ”B” and “C”) X (Line to Line Volts) X TF) / 1732. 05 = KVA • Note: With 4 -Wire Wye and 2 CT’s use the above and multiply the outcome by 0. 8666 to prove for 15 KVA
The Deep Dark Secrets of CT’s and VT’s Presented By Larry Chapman 16
Current Transformers • When and why do we use them? • What are their dangers and weaknesses? • What are shunts all about and who needs them? • What about CT Ratios, Turns Ratios and Effective Ratios? • What does a Burden Rating and/or a Burden Test have to do with anything? • What is Rating Factor all about and who really gives a Rip? • What information on the nameplate is pertinent? 17
Voltage or Potential Transformers • When and why do we use them? • Last, but definitely not least, what happens to billing information from the meter and is the billing multiplier effected? • Should meters still be protected from surges if VT’s are in use? • What are their dangers and weaknesses? • What about Accuracy Class? • What about Burden Ratings? • How should they be protected and how can we be protected from them? Once we know and understand the answers to these questions CT’s and VT’s are a piece of cake. 18
Current Transformer Discussion Current Transformers are used to bring large loads down to a current that is save for us, as meter people, to deal with. Remember, A Meter is NOT a switch. Another fact to consider is the ability to handle loads above 200 amps in a meter socket. In today’s world we do have available Class 320 and Class 400 meters that can, when properly installed, handle their respective rated loads. Inadvertently install a Class 320 meter in a Class 200 meter socket and a potential fire hazard is created. Install a Class 200 meter in Class 320 meter socket and an overload on the meter can occur leading to not only inaccurate billing but also, eventually, another fire hazard. 19
More CT Discussion The class 400 meter is actually bolted in place and, if proper torque is applied when connected, is quite safe. How many service vehicles are carrying a torque wrench. If a fire is proven to start at the meter socket you can rest assured every lawyer in the country is coming after the deepest pockets involved. Other problems include special adapters for testing as well as the sometimes risky means of removing these meters for test. When a load exceeds the limits of a class 200 -meter socket my recommendation will always be to use Current Transformers! 20
CT Discussions Continue Keep in mind, meter people never deal with loads in excess of 10 amps and 120 volts to neutral anyway, the wires just bend easier. Current Transformers can hurt you. There is an extremely high voltage present when load is applied with the secondary circuit open. This voltage dissipates rapidly and would generally result in a burn or simply a shock not unlike an electric fence contact. In the event the CT is a bar type winding, used in all Primary Metering applications and some earlier secondary units, an open secondary can result in the destruction of the CT in a very noticeable manner. 21
Most CT’s in use today are “Window” or “Doughnut” type CT’s. These devices will not fail with an open secondary. Actually CT’s removed after extended periods of open conditions have tested as accurately as they did when built. The metering accuracy at the sights was terrible however due to the loss of indication on the respective phases involved. For personnel safety a shunt across the secondary winding is provided with all CT’s when shipped. The shunt is in the closed position at the time of shipment to allow protection should the CT be installed and load applied prior to the installation of the meter socket and meter. This shunt MUST be opened after meter installation or loss of revenue occurs. The meter will NOT stop, as many believe. In a perfect world the best the meter could do is register 50% but it will register something and sometimes lull the unsuspecting in to going home “Fat, Dumb & Happy”, only to find later they have been giving Kilowatts away for years. The shunt should, however, not be discarded. You may need it again someday. 22
Current Transformer Nameplates The nameplate informs us of the CT’s Ratio, Burden Class, Thermal Rating, Accuracy Class and design of the secondary windings. Something to bear in mind is that attaching this nameplate is the last thing done before it goes out the door. There is no guarantee the correct nameplate was installed at the factory and all CT’s should have a recorded acceptance test run prior to installation. The ratio of a current transformer is simply a mathematical comparison of the current applied to the primary core of the CT and the output current of the secondary windings of the device. All CT Ratios are presented as ###/5. A 200/5 CT will deliver 5 Amperes of secondary current to a meter coil when the consumer’s total load through the CT is 200 Amperes. 23
CT Turns Ratios This brings us to Turns Ratio’s. By presenting the same load to a CT multiple times we “Effectively” divide that CT’s ratio by the number of times we presented the load. IE: If we pass 200 amperes through a CT once the ratio of the 200/5 CT remains 40/1. If we pass the same 200 amperes through the same CT it will be seen again and will present a second 5 amperes of secondary current to the meter coil. The meter does not know this is the same service load originally presented and simply adds another 5 amperes to its original 5 for a total of 10 amperes at the meter. The fact that we have lied to the meter will not effect the actual CT Ratio as it now sees 200+200 amperes for a total of 400. The meter now sees 5+5 amperes for a total of 10. A CT Ratio of 400/10 remains 40/1. 24
Effective CT Ratio Our problem is that we have tricked the CT into presenting the same load to the meter twice, and unless we really have a problem with this consumer, we do not want to bill him double. This is where the term “Effective Ratio” comes into the picture. A simple formula to determine this value is: CT Ratio Turns Primary IE: As depicted above, a 200/5 CT with Double Primary equals: 200/5 or 40/1 2 2 This will yield an “Effective Ratio” of 20/1 and is the value required in any billing multiplier calculation. 25
Burden Class, Thermal Rating Factor and Burden Testing The Burden Class and Thermal Rating are both required to be displayed by ANSI standards. All we really need to understand is if a CT is ANSI rated it will carry the burden of 50 feet of #12 wire and up to 4 electric meter current coils without a significant drop in accuracy. It will also carry (Rated Current X its Rating Factor) in a free air environment of around 86 Degrees forever, and do so, accurately. A Burden Test is something that should be conducted at any time you are at the metering sight. This test can help you find problems with a CT, or the wiring to it, before you actually start loosing revenue. Nothing on the nameplate or the test report sent with a CT indicates the accuracy at less than 10% of rated current. This is why we really do need to be concerned with the Rating Factor 26
Current Transformer Rating Factors ALWAYS load a CT as far into the envelope of the high end as you possibly can. If you make a habit of buying class 20 transformer rated meters and push the CT up into the upper regions of its rating factor you can rest assured the meter is getting the best chance it can to see all the load. The only time this practice can cause any trouble is when using a mass memory device for load profile information. It is possible to saturate the recorder with more pulses than it can record in a given time period. This problem is addressable in the software of all the equipment. Just keep it in mind when setting things up. Recently some of the low end CT’s have been failing the burden test at “. 1 Ohms”. The thing is, when you read the name plate, that’s all they are rated for. DON’T Buy cheap Stuff! You get what you pay for. 27
Voltage Transformers • Voltage Transformers! Old guys call these things Potential Transformers and some people, in the business of selling metering equipment, call them obsolete for voltages below 600 Volts. • If the customer requires any voltage in excess of 240 Volts, Phase to Phase, ABSOLUTELY ALWAYS use voltage transformers. 480 Volts exceeds the level required to induce the ionization of air and is an absolute bomb waiting to explode in a meter socket. • All that is required is enough impurities in the air around a source of ignition and a voltage potential above 360 volts. At this voltage amplitude, given a source of ignition, breathable air will BURN!! 28
Voltage Transformers (Cont’d) • The arc generated by removing potential voltage from a meter can be that source. A 480 -Volt arc will not stop burning until the wire is gone or the voltage potential is removed. • #12 wire will not trip the breaker, or blow the fuse in a 500 KVA transformer but it sure will make a big, bright, blue ball of fire! • Use of these things does require some extra effort and consideration. H 1 and H 2 are the designation symbols for the high voltage, or primary side, of a VT. X 1 and X 2 are the designation symbols for the low voltage, or secondary side, of a VT. • Don’t make the mistake of connecting this guy backwards. There will be a VERY LOUD noise, a black cloud around the area it was mounted in. Stains in your shorts are also common if you are very close! 29
Loading & Protecting Voltage Transformers • A Voltage Transformer cannot carry significant load; it is designed to carry potential voltages only and is usually rated from 25 to 300 Watts. • Fusing the primary side is common in Substations and recommended. • Fusing the secondary side at 1 amp and providing voltage conditioning, in the form of some type of surge suppression, is also recommended on the secondary side. • This can provide extra protection for the metering package and may help the new multi-function solid state equipment installed actually live for 10 years or so. 30
Accuracy of Voltage Transformers • The accuracy of voltage transformers as well as the burden rating is on the nameplate. The accuracy must be ANSI rated to use any voltage transformer for potential to a billing meter. • The burden capability must provide for enough wattage to run any equipment intended at the metering sight. This includes recorders, remote telephone modems, meter shack lighting etc. • Keep all these things in mind when determining the correct VT’s for a sight. All VT’s must carry the same accuracy class and burden rating. • Don’t go out there and hang a 3 KVA house service transformer to make a metering VT. It’s not accurate enough, and besides it’s not legal! 31
VT Ratio’s & Multipliers • • • • • VT Ratio’s are usually marked as 7200/120 or 480/240 or 300/120 etc. This depicts the high or input voltage to the low or output voltage. Multipliers are either involved in the actual billing or in determining what register will be used on the meter to eliminate the need for a multiplier. In the case of Solid State metering they can be used to force the meter to use primary readings. With Mechanical meters always use the multiplier formula: Kr = Kh X Rs X Rr X TF Where TF = CTr X VTr 1000 Turns Primary at the CT With Solid State meters it is always best to leave the meter programmed at nameplate Meter Kh and apply transformer factor as the billing multiplier. 32
Meter Form Numbers What do they mean? By Larry Chapman 33
Single Phase 120 Volt, 2 -Wire Service. Signs, Lighting, phone booth Etc. Single Phase 240 Volt, 3 -Wire Service. Probably 90% of the electric services in operation today. 34
The 1 S Meter • • The 1 S meter can only be used in a Single Phase, 2 -Wire application. In today's world the only place these are practical is on a telephone booth or possibly sign lighting. Caution must be taken not to place a Form 2 S meter in this service or to place this meter in a service requiring the Form 2 S meter. The resultant errors are many and will be discussed during the course of this seminar. Suffice it to say both under billing and over billing can occur in either case. 35
The 2 S Meter • • • The 2 S meter can only be used in a Single Phase, 3 -Wire application. This meter makes a compromise on voltage balance to allow metering a 3 -Wire load with single element meter. Caution must be taken not to place a Form 2 S meter in a 2 -wire, 120 volt service or in a network metering application. This meter, in a network service, will return 86% on the delivered kilowatts if the load is perfectly balanced and power factor is unity. 36
Multipliers • Make sure any automatic shunting devices in the meter socket are working properly. A closed shunt after the meter is set in place does not stop the meter. It only slows it down drastically. • Caution must be taken involving the use of register ratio's to adjust the billing multiplier. Work the appropriate multiplier formula for any installation this meter is involved with. Kh. X Rs X Rr X TF = BILLING MULTIPLIER. 10, 000 The recommended Billing Multiplier with Solid State Meters is the. Transformer Factor. CTr X Vtr = TF Turns Primary at the CT 37
The 3 S Meter • The 3 S meter is the most versatile of all single-phase meters. Once the need for transformer rated metering is established this meter can be used on any 2 or 3 -Wire single-phase load. • Remember that a network service is not a single-phase load. • At least one current transformer will always be involved with the use of this meter. Any time this meter is removed from a service the related Current and Voltage transformers should be tested as well as properly shunted or protected during the time the meter is removed. Make sure any automatic shunting devices in the meter socket are working properly. A closed shunt after the meter is set in place does not stop the meter. It only slows it 38 down drastically.
3 S Meter Continued • Caution must be taken involving the use of register ratio's to adjust the billing multiplier. Work the appropriate multiplier formula for any installation this meter is involved with. Kh. X Rs X Rr X TF = BILLING MULTIPLIER. 10, 000 The recommended Billing Multiplier with Solid State Meters is the. Transformer Factor. CTr X Vtr = TF Turns Primary at the CT 39
4 S Meters • • • The 4 S meter is the "Transformer Rated" version of the form 2 S meter and makes all the same compromises. This meter is not one bit more accurate in service than a Form 3 S meter. The only time it is needed is, in the event load wires are too large to pass through the Current Transformer more than once. As with any "Transformer Rated” installation, all Current and Voltage transformers should be tested as well as properly shunted or protected during the time the meter is removed. 40
4 S Meters Continued • Make sure any automatic shunting devices in the meter socket are working properly. A closed shunt after the meter is set in place does not stop the meter. It only slows it down drastically. • Caution must be taken involving the use of register ratio's to adjust the billing multiplier. Work the appropriate multiplier formula for any installation this meter is involved with. Kh. X Rs X Rr X TF = BILLING MULTIPLIER. 10, 000 The recommended Billing Multiplier with Solid State Meters is the. Transformer Factor. CTr X Vtr = TF Turns Primary at the CT 41
1 -Phase, 3 -Wire Network This application being described as a single phase service Is misleading, to say the least. It is not possible to build a network voltage without using a 3 -Phase, 4 -Wire, Wye transformer bank. Typically this service is used to provide a single phase solution for apartments, to better balance the loads on the service transformer, or a nearby home when a large “Wye” bank is already set to serve a school or business adjacent to the location. 42
12 S Network Service • The 12 S is also common for use on a “Network Service”. Network metering is applied when only 2 phases of a 3 Phase 4 -Wire WYE transformer are being used to provide service voltage to a consumer. IE: Apartment buildings, shops in a mall ETC. This commonly will provide only 208 Volts to the consumer and motorized equipment must be set up to run properly on this voltage. • Never install a Form 2 S meter in a service requiring a 12 S meter. In any case the meter accuracy will be less than 75% registration. 43
5 S Network Service • The 5 S meter is a "Transformer Rated" meter capable of metering Any and All loads. The absolute most versatile meter made. • Make sure you follow an accepted wiring scheme. • Use extreme caution when you get "Creative" with this meter. 44
Multipliers • Make sure any automatic shunting devices in the meter socket are working properly. A closed shunt after the meter is set in place does not stop the meter. It only slows it down drastically. • Caution must be taken involving the use of register ratio's to adjust the billing multiplier. Work the appropriate multiplier formula for any installation this meter is involved with. Kh. X Rs X Rr X TF = BILLING MULTIPLIER. 10, 000 The recommended Billing Multiplier with Solid State Meters is the. Transformer Factor. CTr X Vtr = TF Turns Primary at the CT 45
3 -Phase, 3 -Wire Delta Not the most popular configuration today, but it still exists and must be metered Properly. There can never be a ground connection made on the “X 0” bushing or any of the center tap “X 2” bushings. Grounding the phase that is presented to the meter as the “Common” voltage is highly recommended and actually required in many states. 46
12 S 3 -Phase, 3 -Wire Delta • The 12 S meter is used in 3 Phase 3 -Wire services of all voltage ranges. Remember this is a 2 -element meter and cannot be used on any 4 Wire application. On a 3 phase, 3 -wire service it is common but not always required to ground the phase presented to the meter as the “Common” voltage phase. • If this metering package is implemented on a 4 -wire transformer connection the voltage phase not connected to the meter socket lugs remains hot, regardless if the meter is removed, and the resultant danger to personnel is very real. 47
5 S 3 -Phase, 3 -Wire Delta • The 5 S meter is a "Transformer Rated" meter capable of metering Any and All loads. The absolute most versatile meter made. • Make sure you follow an accepted wiring scheme. • Use extreme caution when you get "Creative" with this meter. 480 Volt 3 -Wire Delta 48
3 -Phase, 4 -Wire Delta The popularity of this configuration is primarily thanks to “Rural Electrification”. The need for 3 -Phase power at services that were largely single phase loads came when farming began to see a need for large motors in drying and moving grain, while the remaining 9 months of the year lighting and other household uses were dominant. This is also the only 3 -Phase configuration that can be properly built using only 2 primary line phases and 2 single phase 3 -Wire transformers. When these banks are built the transformer intended to carry the single phase portion of the load is larger in KVA rating. Proper sizing would depend on the total KVA of 3 -Phase load as well as the total KVA of the single phase load. IE: An expected 15 KVA 3 -Phase load and 10 KVA single phase load would require a 25 KVA transformer plus a 15 KVA transformer. 49
15 S Meter • • 15 S The 15 S meter is the selfcontained version of the 8 S "Transformer Rated" meter. This meter actually meters the single phase portion of a 3 Phase, 4 -Wire, DELTA service exactly the same as a Form 2 S meter does a normal Single Phase 3 -Wire service with the left element. The "Wild Leg" is then metered by the right element of the meter. The most common mistake on the 4 -Wire DELTA service is connecting the "Wild Phase" to the wrong coil of the meter. This voltage and current absolutely MUST be presented to the right element of the meter. The resultant loss of revenue is approximately 18% when this error is left uncorrected. 50
15 S Discussion • A 14 S mechanical meter installed in the 15 S service can register anywhere from 40% to 140%, depending on the location of the “Wild Phase” and the consumers load balance. This problem has been known to cause severe discontent among the natives. • A 16 S mechanical meter installed in the 15 S service will actually run correctly as long as the right voltage coil stands up to the high "Wild Phase" voltage. With mechanical meters the voltage coil failure is imminent, and once the failure occurs a loss of 1/3 of all consumption created by 3 -Phase equipment will take place. • Today's Solid State, "Multi-Form", meter is actually nothing more than a 16 S meter. The fact that its voltage coils are wide range coils capable of being very accurate at all voltage ranges make it compatible with this application. 51
Multipliers • Make sure any automatic shunting devices in the meter socket are working properly. A closed shunt after the meter is set in place does not stop the meter. It only slows it down drastically. • Caution must be taken involving the use of register ratio's to adjust the billing multiplier. Work the appropriate multiplier formula for any installation this meter is involved with. Kh. X Rs X Rr X TF = BILLING MULTIPLIER. 10, 000 The recommended Billing Multiplier with Solid State Meters is the Transformer Factor. CTr X Vtr = TF Turns Primary at the CT 52
8 S - 4, Wire Delta • • • The 8 S meter is a "Transformer Rated" meter that actually meters the single phase portion of a 3 -Phase, 4 Wire, DELTA service exactly the same as a Form 2 S meter does a normal Single Phase 3 Wire service with the left element. The "Wild Leg" is then metered by the right element of the meter. The most common mistake on the 4 -Wire DELTA service is connecting the "Wild Phase" to the wrong coil of the meter. This voltage and current absolutely MUST be presented to the right element of the meter. The resultant loss of revenue is approximately 18% when this error is left uncorrected. 53
8 S Meter Mix Ups • • A 6 S meter installed in the 8 S service will run forward at approximately 33%. This is due to the cross phasing on the B Phase coil and the loss of voltage on the C Phase coil. A 9 S meter installed in the 8 S service will actually run correctly as long as the right voltage coil stands up to the high "Wild Phase" voltage. With mechanical meters the voltage coil failure is imminent, and once the failure occurs a loss of 1/3 of all consumption created by 3 -Phase equipment will take place. Today's Solid State, "Multi-Form", meter is actually nothing more than a 9 S meter. The fact that its voltage coils are wide range coils capable of being very accurate at all voltage ranges make it compatible with this application. One thing the Solid State meter has brought us is the misconception of no longer needing to include step down voltage transformers in the wiring scheme. This is an extremely unintelligent thought process. Any voltage in excess of 240 Volts, Phase to Phase, should be reduced with Voltage Transformers. If management has no concern for the safety of the metering personnel it may help to stress the increased life span of the $300. 00 meter you just installed. 54
8 S 480 Volt • This is not very common, but it does exist. Please use VT’s when you get stuck with this service. • When Mechanical meters were used in this application only two VT’s were required, however, the solid state meter will require third VT to afford a voltage reference to neutral. 55
5 S 4 -Wire, Delta • • • 5 S meters are commonly used with 3 -Phase, 3 Wire Delta configurations. Some of the early Solid State versions of this meter were not compatible for use in 4 -Wire Delta applications. SEE Form 45 S for info on these. As with any "Transformer Rated” installation, all Current and Voltage transformers should be tested as well as properly shunted or protected during the time the meter is removed. Make sure any automatic shunting devices in the meter socket are working properly. A closed shunt after the meter is set in place does not stop the meter. It only slows it down drastically. 56
45 S Vs 5 S, 4 -Wire Delta • The 45 S meter is a Solid State "Transformer Rated" meter capable of metering Any and All loads. The absolute most versatile meter made. • Note the difference in the voltage coil configuration between the 45 S and 5 S • The 45 S actually has 3 voltage coils instead of 2 like the 5 S it replaces. This solved the early problems with 4 Wire DELTA wiring schemes. 57
More 45 S When using VT’s with this meter it is still necessary to use the proper number. IE: 3 -Phase, 3 -Wire use 2 VT’s, 3 -Phase, 4 Wire use 3 VT’s with the exception of a configuration that mimics the 6 S meter. 58
The 24 S Heaven Forbid! • • The 24 S meter is the other "Transformer Rated" meter that should have never been made. It is the same engineering nightmare as the 7 S with some major problems added in. These meters should be retired and replaced by an 8 S wiring scheme whenever the chance presents itself. The 24 S meter has 7 terminals. They are exactly the same bayonet configuration as the selfcontained CLASS 200 Form 14 S, 15 S and 16 S meters. This meter, plugged in to any one of those sockets will EXPLODE! 59
24 S Headaches • Keep in mind that if you inadvertently install a 14 S, 15 S, or 16 S in this meter's wiring scheme it will also attempt to explode. The only difference is the wire to the meter socket in a transformer rated application is usually small enough that the meter wins. This will still cause a very bright blue flash and the potential for some serious burns to hands and faces. • The 7 S will run forward if inadvertently installed in this 3 Phase, 4 -Wire, DELTA, 24 S wiring scheme. Registration can vary from 40% to 140% if this occurs and the consumer will never believe you if you let him in on this little secret and then try to tell him his service was at the 40% level. Another thing to remember, the voltage coils of the 7 S meter are commonly 120 Volts and will not live long under these conditions. 60
3 -Phase, 4 -Wire Wye This is the most versatile and practical transformer configuration in use today. Load balance, voltage requirements and safety are all much easier goals to meet with this configuration than any of the rest. It requires 3 primary phases to produce it and it provides 3 secondary phases of equal voltage to ground for consumer applications. 61
14 S Meter • The 14 S meter is a “selfcontained Class 200 meter that, like the "Transformer Rated" 6 S, meter blows all engineering theory out the window. It is less accurate than the 16 S in applications where voltage may vary but not enough to justify its replacement. • This meter is not manufactured as a solid state meter. Its solid state replacement is called the Form (14 S, 15 S, 16 S). As long as you remember the 14 S, mechanical meter cannot live with a 4 -Wire, DELTA service and a 15 S, mechanical meter cannot live with a 4 -Wire WYE service you should be OK. 62 Wiring
14 S (Continued) • The most common error involving this meter is replacing it with a Form 15 S meter. The 15 S meter is for 3 -Phase, 4 -Wire, DELTA service. This error will result in a 15% Loss of Revenue with a balanced load. • Always take voltage readings at the points in the socket where the meter makes contact. This will help you prevent a mistake of this nature. • The 16 S mechanical meter in this service is OK. • NEVER install a Form 7 S or 24 S meter in this socket! It makes very loud noises! 63
16 S Meter • The 16 S meter is the selfcontained version of the 9 S "Transformer Rated" meter. This meter, in Solid State form, is the only 7 terminal meter you need. If you study the self-contained 4 Wire meter socket diagrams you will see they are all identical. • Remember the limiting factor of the 16 S mechanical meter is the inability of the voltage coil to withstand the “Wild Phase” voltage. It cannot be installed in the 3 -Phase, 4 -Wire, DELTA service for this reason. 64
More 16 S Notes • A 14 S meter installed in the 16 S service is not a problem as they are both designed to do the same job. • The configuration of the 15 S mechanical meter will cause a loss of revenue equal to approximately 18%in the 4 -Wire, WYE application. 65
You will Get Tired of This Slide • Make sure any automatic shunting devices in the meter socket are working properly. A closed shunt after the meter is set in place does not stop the meter. It only slows it down drastically. • Caution must be taken involving the use of register ratio's to adjust the billing multiplier. Work the appropriate multiplier formula for any installation this meter is involved with. Kh. X Rs X Rr X TF = BILLING MULTIPLIER. 10, 000 The recommended Billing Multiplier with Solid State Meters is the. Transformer Factor. CTr X Vtr = TF Turns Primary at the CT 66
5 S With Wye Services • • 5 S or 45 S meters used with Wye services can use several combinations. Make sure any automatic shunting devices in the meter socket are working properly. A closed shunt after the meter is set in place does not stop the meter. It only slows it down drastically. One More 67
6 S Meters • • 277/480 Wye The 6 S meter is a "Transformer Rated" meter that blows all engineering theory out the window. It is less accurate than the 9 S in applications where voltage may vary and the billing multiplier is large. Contrary to some "Prune Peddlers" statements, replacement of this meter with the 9 S is not necessary unless it is on a primary metering sight or the multiplier exceeds 300. Once these criteria are met the change may well pay for itself. 68
6 S (Continued) • • The most common error with a 6 S is forgetting the jumper from neutral to the #17 position, the second connection down on the right side of the socket, when wiring the socket at the job sight. The second most common error is installing one of the other 13 terminal meters in its place. A 36 S meter installed in the 6 S service will run correctly and the only danger is damage to the "KYZ" output if it is used. 69
More 6 S Concerns • An 8 S meter installed in the 6 S service will meter approximately 86% of the consumption on phases A & B and have no potential at phase C causing the loss of all revenue created by C phase. • A 9 S meter installed in the 6 S service has a loss of potential at C phase plus the fact that B phase current is presented to C phase voltage on the center element. The end result of this problem is accurate registration for A phase, 50% negative registration for B phase, and no registration for C phase. • The most disturbing fact of any of these conditions is that in all cases, with a balanced load, the meter will run forward. 70
Still the 6 S • • • The onset of today's Solid State, "Multi-Form", meter has also caused some confusion. The 6 S meter wiring scheme must have a 6 S or 36 S meter installed. The only exceptions to this is are meters from General Electric and Itron that are actually 9 S meters with the programming capability of being told it is living under 6 S conditions. ANSII dubs this wiring scheme a 46 S but the meter manufacturers have chosen to ignore that little technicality. The socket MUST be re-wired in accordance with the manufacturers respective wiring diagrams. The only time this trick is recommended is when you are dealing with a primary metering application and do not have the option of adding a Voltage Transformer to allow use of the proper 9 S wiring scheme. In reality this was a very dumb idea !!! 71
36 S Meter • The 36 S meter is actually a 6 S "Transformer Rated" • meter with all voltage returns connected to 1 common return. It is less accurate than the 9 S in applications where voltage may vary and the billing multiplier is large. The most common error with a 36 S is replacing it with a form 6 S and forgetting the jumper from neutral to the 6 th position 7 center terminals, when wiring the socket at the job sight. 72
More 36 S • The second most common error is installing one of the other 13 terminal meters in its place. • An 8 S meter installed in the 36 S service will meter approximately 86% of the consumption on phases A & B and have no potential at phase C causing the loss of all revenue created by C phase. • • A 9 S meter installed in the 36 S service has a loss of potential at C phase plus the fact that B phase current is presented to C phase voltage on the center element. The end result of this problem is accurate registration for A phase, 50% negative registration for B phase, and no registration for C phase. Just remember that in any combination, with a balanced load, the meter will run forward and lose money. 73
Even More 36 S • The onset of today's Solid State, "Multi-Form", meter has caused some confusion. The 36 S meter wiring scheme must have a 36 S meter installed. Adding a ground wire to the 6 th position will allow replacement with a 6 S • As with any "Transformer Rated” installation, all Current and Voltage transformers should be tested as well as properly shunted or protected during the time the meter is removed. Make sure any automatic shunting devices in the meter socket are working properly. A closed shunt after the meter is set in place does not stop the meter. It only slows it down drastically. 74
The 7 S Disaster • The 7 S meter is a "Transformer Rated" meter that should have never been made. It is the same engineering nightmare as the 6 S with some major problems added in. • These meters should be retired and replaced by a 9 S wiring scheme whenever the chance presents itself. • The 7 S meter has 7 terminals. They are exactly the same bayonet configuration as the self-contained CLASS 200 Form 14 S, 15 S and 16 S meters. This meter, plugged in to any one of those sockets will EXPLODE! 75
More 7 S • Another interesting concern is that if you inadvertently install a 14 S, 15 S, or 16 S in this meter's wiring scheme it will also attempt to explode. The only difference is the wire to the meter socket in a transformer rated application is usually small enough that the meter wins. • This will still cause a very bright blue flash and the potential for some serious burns to hands and faces, not to mention the possible need for an underwear change. • Installing a 24 S in this socket will cause the meter to register approximately 86% of the consumption on phases A & B and have no potential at phase C, causing the loss of all revenue created by C phase. Actually the same problem as installing the 8 S in the 6 S application. 76
Multipliers • Make sure any automatic shunting devices in the meter socket are working properly. A closed shunt after the meter is set in place does not stop the meter. It only slows it down drastically. • Caution must be taken involving the use of register ratio's to adjust the billing multiplier. Work the appropriate multiplier formula for any installation this meter is involved with. Kh. X Rs X Rr X TF = BILLING MULTIPLIER. 10, 000 The recommended Billing Multiplier with Solid State Meters is the. Transformer Factor. CTr X Vtr = TF Turns Primary at the CT 77
The 9 S Meter • • The 9 S meter is a "Transformer Rated" meter that can actually meter any service known when wired properly. The only limiting factor of the 9 S meter is the voltage coil's ability to exist with whatever voltage is applied. The Solid State version of this meter, with wide range voltage transformers, has revolutionized the metering industry. Called the "Multi. Form 8 S-9 S" meter, many “Prune Peddlers” have misrepresented it as the replacement meter for all 13 terminal metering applications. This is not the case. 78
9 S - 277/480 Wye • The 4 -Wire Wye 277/480 Volt installations should all use VT’s to allow maximum protection at the meter socket. Just keep in mind that the possibility of miswiring the installation increases dramatically when we add 12 more connection points to the combination. • The “Two Sockets-Two Meters” VT Pack works very well in this application. Keep in mind these VT’s are only rated at 90 VA, so do not utilize them to energize additional equipment. IE: Recorders, external AMR devices or load control equipment. 79
9 S Discussion • General Electric has the new KV Meter that does have the capability of replacing any 13 terminal meter, however you must adhere to the wiring schemes and programming requirements set forth in their "Fitzall Applications Manual". • A 6 S meter installed in the 9 S service will run forward at approximately 33%. This is due to the cross phasing on the B Phase coil and the loss of voltage on the C Phase coil. • An 8 S meter installed in the 9 S service will create a loss of about 18% due to the single phase element of the meter not having a neutral reference. • 9 S meters should not be confused with 10 S meter. The difference is the 9 S has a single voltage common at the right most position of the 7 center terminals. The 10 S meter has the voltage common of each coil separated and connected to the 5 th, 6 th, and 7 th terminals respectively. 80
9 S / 10 S Discussion • • FORM 10 S The 10 S meter was designed for use as a reactive meter, either a KVAR meter or a KQ meter and is not used in the solid state world since reactive data is something the solid state meter easily provides. Those of you involved in substation or power plant metering may still run across this meter but I suspect it is gradually being replaced and phased out. The 9 S meter will probably become the standard meter base for Polyphase applications in the future. There is already a class 200 form 9 S meter available for use with the "Two Sockets Two Meters" companies’ self-contained metering application. As these things develop I am certain new form numbers will be assigned to help prevent confusion, but for now just watch for them. Again, do not accept the misconception that we no longer need to include step down voltage transformers in the wiring scheme. Any voltage in excess of 240 Volts, Phase to Phase, should be reduced with Voltage Transformers. • It’s all about YOUR personal Safety !!!! 81
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