Introduction to Solid State Meter Testing. Terms and Definitions

Transcription

1 NWEMS Introduction to Solid State Meter Testing 2017 Northwest Electric Meter School Presented by: Marcus Zickefoose Radian Research Inc. Terms and Definitions Term Definition Accuracy Calibration Class Designation Creep The extent to which a given measurement agrees with the defined value. Typically stated as percent registration or percent error. Comparison of the indication of the instrument under test, or registration of meter under test, with and appropriate standard. The maximum of the watt hour meter load range in amperes. A continuous motion of the rotor of a meter with normal operating voltage applied and the load terminals open circuited. Form Number The form number is a number given to a meter, by the ANSI C 12 committee that defines how the meter is internally wired and the test parameters of the meter. 1

2 Terms and Definitions Term Instrument Transformer Test Amps Test Volts K h Watthour Meter Constant K t Watthour Meter Test Constant Definition A transformer that reproduces in its secondary circuit, in a definite and known proportion the voltage or current of its primary circuit, with the phase relationship substantially preserved. The test amps or TA is the full load current which the meter should be calibrated and this value is defined on the meter s nameplate. The test voltage or TV is the value of the voltage which the meter should be calibrated. The TV is located on the nameplate of the meter. The expression of the relationship between the energy applied to the meter and one disk revolution or equivalent. The expression of the relationship between the energy applied to the meter and the corresponding occurrence of one test output indication. Terms and Definitions Term Definition VTR Voltage Transformer Ratio CTR Current Transformer Ratio The ratio of the rated primary voltage to the rated secondary voltage as stated on the nameplate. The ratio of the rated primary current to the rated secondary current as stated on the nameplate. 2

3 Major Differences In Solid State Solid State No moving parts High accuracy, no drifting Easy to install AMR/AMI module Programmable to display multiple metering quantities Meter failures are normally easy to identify One meter can work in multiple services Mechanical Moving parts that can slow down over time AMR / AMI modules may not be available and are difficult to install Can fail over time and as long as disk spins hard to tell if there is a problem Meter designed specifically for a service Life is Simpler.Right? A few meters fit all Multi Form Multi Voltage Multi Mode (Energy Units) Modem / Ethernet AMI Capabilities 3

4 BUT.Life is Also More Complicated How do you test them correctly? What are differences when testing a SS or mechanical meter What are the required test points What quantities do you test What form number do you test them as Solid State Testing Voltage & Current Test Points ANSI FL, LL, PF Customer Load What Quantities do you test? Watts Vars VA Bi Directional 4

5 Solid State Testing How do you test multi form meters? Example: 16S(14,15,17S) Refer to meter manufacturer s manual Recommend to test by form number outside of parentheses If you want to test as a delta, select 16S with a delta service type Self Contained This type is designed to be metered without the aid of other devices such as transformers. It is called self contained because the meter has all components contained to properly meter the service. Common Forms: 1S, 2S, 12S, 14S, 15S, 16S, 17S 5

6 Transformer Rated This type is designed to be used with current transformers (CT) and/or potential transformers (PT). This service will have high current and/or high voltage so the meter monitors the service by taking a small sample of the service. The readings of the meter are then scaled by the sample size. 3S, 4S, 5S, 6S,7S, 8S, 9S, & 10S Obsolete Types: 7S & 10S» S Base (Socket Type) Types of Meter Bases ANSI Standard Configuration for SC or TR» A Base Bottom connected without a meter base, bare wires are connected directed to the bottom of the meter.» Switchboard / Rackmount Substation or Powerplant Mounted in a case with a terminal strip on the back of the meter for wiring» K Base Bolt in Meter designed for higher current applications Only supported by L&G 6

7 Do Solid State Meters Need Tested?» If you plan on billing their readings Electric meters are precision instruments Any billing complaint can bring the accuracy of the meter into question and end up in court» Ensure the accuracy of the meter» Ensure proper functioning of the meter AMI Installation Proper service wiring Do Solid State Meters Need Tested?» In some areas there are regulations» All meters have the ability to drift over time, nothing is 100% perfect» All meters, CT s, and PT s are manufactured to a certain spec that can be affected by external sources so routine verification protects your flow of revenue. 7

8 Watt hour Meter Testing Equipment Typical Items Needed For Testing» Reference Standard Watt or Watt/Var» Test Kit or Load Box» Test Jack, Test Switch» Multi Meter (Volts, Amps, Ohms)» Hand tools, Safety Equipment (PPE) Methods for Testing: Shop Testing System 1. The meter is being tested and calibrated in a controlled environment. 2. High volume testing, meter deployment 3. Voltage and Current are synthesized for maximum accuracy. 4. The test system is automated and little interaction is needed. 5. Results are automatically saved to a company database 8

9 Why Test Meters in the Field?» With AMI systems, personnel are visiting metering sites less and less» Increased Customer satisfaction and confidence from observing the test» Immediate results for the customer» Limited paper shuffle for Utility» Meter tested in an as found condition» Portable standards very accurate Methods for Testing: Reference Standard with Phantom Load 1. The meter being tested is isolated from the customer s service by using a Test Jack or by opening Test Switches. 2. A Phantom Load is used to generate a controlled load for testing the meter. 3. A Portable Watthour Standard is wired in series with the revenue meter. The accuracy of the meter is checked against the Standard. 9

10 Methods for Testing: Reference Standard with Customers Load No need to isolate meter from customer s load. Independent measurement of customer s voltages and currents. Displays Voltages, Currents, Phase Angles, Power and Power Factor Test data is saved in internal memory and can be downloaded to PC Test meter accuracy in real world scenario Not Suitable for Performing Calibration Methods for Testing: Field System Test With Site Analysis Performs an ANSI meter test and customer load test Tests CT s, PT s and transducers Waveform and harmonic analysis Test meter accuracy in real world scenario Test data is saved in internal PC that can be downloaded to a central database in the shop 10

11 Bi Directional Meters» Bi Directional measurement & testing One meter can measure delivered & received energy Delivered is what you sell to consumer Received is what they generate If meter is on a generator then this could be reversed Register can display it in different ways Separate Delivered and Received quantities A NET quantity (delivered received) Can you test delivered & received? Computerized boards have an electronic way to reverse power You can manually reverse the line and load on test kit wiring Automated Testing of Multi Mode Meters 4 Quadrant Testing (Dynamic Sequence) Each step of the test sequence Load Voltage, Current, Phase Direction Forward, Reverse Mode Watthours, VARHours Automatic Energy Mode and Flow Direction Switching Would need to pause and change meter IR pulse energy modes 11

12 Physical Issues Infrared Test Pulses have No Moving Parts Pro - Test socket doesn t need to be level Con Test Pulse emitted from a Light Emitting Diode Infrared Test Pulses - What are they? Infrared is Heat Energy Usually invisible Have to know where to look Different Manufacturers pulses have different Locations Modes combined or separate WattHr and VARHr pulses Strengths Physical Issues Infrared Test Pulses - Where are they? Optic Coupler Test and communication with same LED - Cost savings Some test equipment mfr s can detect using Modified Coupler Makes for a light tight connection Front Panel or Top Firing Optical probe must be able to reach Some test equipment mfr s offer Light Pipe extension Critical Needs to be close to block natural room infrared See IR Pulses with phone camera Doesn t work with all HD smart phone cameras 12

13 When Kt Does Not Equal Kh First electronic meters Made to emulate mechanical meters Disk emulator One pulse per revolution New Designs Program multiple pulses per revolution (Kt not Kh) ABB Alpha - 24 Pulses per revolution (1 pulse in Test Mode) Advertised to Simplify and Speed Up Testing Does not mean one pulse is sufficient for accurate, repeatable testing Non Standard Kh New Designs Designed with non-standard Kh Itron Centron 2S Residential Kh (normally 7.2) GE I-210 Kh 10.0 and Kt 1.0 Customer Requests Programmed with non-standard Kh 9S Residential Kh (normally 1.8) Advertised to Simplify and Speed Up Testing Does not mean one pulse is sufficient for accurate, repeatable testing 13

14 Settling Time Manufacturers are specifying minimum time for voltage to be applied to meter before the first test starts Why Multi form meters are determining and adjusting to the applied service Meters with communication modules send out messages over port to see if configuration program is attached If test starts too soon, test equipment incorrectly interprets communication module pulses as energy pulses Element Testing Pro Only way to verify element balance Only way to test for Cross Wiring (potential and current elements mismatched) if doing single phase testing Con Considerable extra time required for slow element tests 14

15 Record Keeping Your Meter Test Records Are Legal Documents Data collection and test records must be accurate Make sure data is backed up regularly Take readings - rescue the billing dept Document any suspected tampering Automate the data entry Record test reasons Develop a meter testing plan Equipment Accuracy Rotating (mechanical) standards are no longer acceptable Type of equipment Accuracy verifier Calibration device Accuracy class Does your manufacturer consider all uncertainties? Typical or Maximum Error Accuracy? Testing report 15

16 Traceability Verify purchased test equipment is traceable to NIST Have a regular program to maintain traceability Standards Compare - Manual or Automated process to compare internal test board electronic standard to external Transfer standard Send Standards to Calibration Lab Maintain a Transfer Standard within the utility Rent a transfer standard from a Calibration Lab Hire a Recertification Expert Meter Testing in Review» Watt hour Meter Testing is important to your company and the customer for verification of watthour metering» We test in the field because it is provides more confidence to the customer and sometimes less expensive for the company» We test in the shop because we need more environmental control to perform calibrations.» It is important to keep good documentation for future reference. 16

17 Final Thoughts When in Doubt Read the manufacturer s documentation Call the manufacturer s technical support Call the test equipment vendor s technical support Meters are the cash registers in the field 24/7/365. Their accuracy affects your flow of money. 17