MeterTesting an Electromechanical Meter

Practical Example of Use

2OMICRON Test Universe

Manual Version: Expl_Meter_ElmechMeter.ENU.1 - Year 2013

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Meter1 Meter

1.1 About MeterMeter is a test module for testing electronic and electro-mechanical energy meters with a meter class of up to 0.2S1 for the following types:

Watt-hours (Wh)

var-hours (varh)

VA-hours (VAh)

V-hours (Vh)

V2-hours (V2h)

I-hours (Ih)

I2-hours (I2h)

Q-hours (Qh)

The Q-hour meter is a regular watt-hour meter that is installed with the potential circuits wired one phase behind the standard watt-hour connection (lagging the watt-hour connection by 60 degrees).

Multifunctional, i.e., meters with more than one pulse output and various physical quantities of the above-mentioned types.

Once the parameters for a particular meter have been entered in the module's test object parameter section, the data can be saved to be used again later. For the test, a meter is connected to the OMICRON CMC test set and its corresponding data file is reloaded.

Meter can be used with the following test equipment:

CMC 56

CMC 156

CMC 151

CMC 256

CMC 256plus

If the meter under test has more than one output, all of these outputs can be connected to the CMC's binary inputs at the same time. Meter is then configured accordingly and measures these outputs sequentially.3

1. Depends on the test hardware used

4OMICRON Test UniverseThe meter tests can be carried out in four different modes:

load test (meter error test with or without a reference meter; in the case of a load test without a reference meter, a correction table can be used to compensate for CMC measurement errors)

mechanism test (test of total meter error, i.e., test of both the meter's measurement and counting unit)

injection test

no-load test

creep test.

The same report functionality that is available for the other test modules of the OMICRON Test Universe is used by the Meter module to format the test reports and to document the test results. In addition, a condensed test report format is available.

The reports are user-defined, serve as verification of a successful test, and can later be used as a template for repeating the test.

1.2 Time Sequence of a Meter TestFigure 1-1:Lapse of a meter test

t

1 2 345

67

V I

0 1 2 3 4 5 6 7 8 9

warm-up time start-up time test object measurement

reference measurement

test object

reference meter

Meter1. Warm-up time:

If the test is started with the icon, the specified warm-up time precedes the actual test.

If the button N O M I N A L V O L T A G E O N is pressed prior to the test and the test is started later, the specified warm-up time is ignored. In this case the warm-up time is the time period between switching on the nominal voltage manually and the start of the test.

2. Start-up time: Here the values that are set in the following test line are output but pulses are not yet recorded.

3. The specified start-up time has elapsed: The start-up time is delayed until the meter under test outputs a pulse.

4. The first pulse received after the specified start-up time has elapsed is the initialization pulse that starts the actual test. However, this pulse is not counted.

The time measurement for the meter under test is started.

5. If the test is carried out with a reference meter, the time measurement for the reference meter is started with the first pulse received from the reference meter after the initialization pulse of the meter under test.

6. When the pulse specified under "Pulses | Nominal" (here pulse number 9) is received, the end of the first test line (line 1 in the test table) has been reached and the program goes to line 2. The time measurement stops when the last pulse is received. Now the time for the test object measurement is known. Independently of the mode, the next test line starts with the start-up time again (topic 2).

7. If the test is performed with a reference meter, the first pulse of the reference meter received after the stop pulse of the meter under test is the stop criterion. Until this moment, the generators remain switched on. Now the time for the reference measurement is known. Normally this time will differ slightly from the time of the test object measurement. To obtain exactly the same time base for both measurements, the energy value of the reference meter is corrected by calculating the meter error by the factor tTO / tRef.

The test continues with the next test line with no interruption of the voltage.

When the last test line is reached, the voltage remains switched on if the button "Nominal Voltage ON" was set.

Otherwise the voltage is switched off after the last test line is passed.5

6OMICRON Test Universe1.3 Meter Example: Testing an Electromechanical MeterSample files:

Meter2-ML266.met

Meter2-ML266.ohc

Meter2-ML266.rio

Stored at:

...OTU installation path\Test Library\Samples\SW Manual Examples\ Measurement

TaskA three-phase meter with the ML266 (Landis & Gyr) induction measuring element is to be tested.

The meter measures "active power import" (Wh.-exp.) and has a backstop for the other energy direction. The rotations of the meter disk are read optically with a photoelectric pick-up head.

The meter is used in a three-phase four-wire system and is connected to the test set accordingly. The meter is connected directly to the voltages (3 x 220 V L-N) and via a 100/5 current instrument transformer.

The specifications of the meter are as follows:

Three-phase four-wire meter for active power

One energy direction

Accuracy: class 0.5 s

Meter disk for a pick-up of the rotations

Vnom: 3 x 220 V / 380 V

Inom: 5 A

Primary pulse rate: 37.5 rotations / kWh which results in 750 pulses / kWh secondary

Pulse width of the pick-up head: approx. 1 ms

MeterThe following test steps are carried out, based on the PTB standard:

Accuracy test for a number of specified test points

Test the creep behaviour

Test the no-load behaviour

Check the counting mechanism

A CMC 256 test set with the Meter software module and accessory equipment (consisting of CMLIB B, power supply for CMLIB B, photoelectric pick-up head SH2003 and connecting cables) is available for the test.

According to the test procedures of the user, a reference meter must be used. For this purpose the three-phase TVE 102/3 (Landis & Gyr) meter is available.

SolutionThe test is carried out with the following steps:

1.3.1 Considerations Prior to the TestThe power resulting from the nominal values is:

P = 220 V x 5 A x 3 = 3300 W

According to the meter constant, one rotation of the meter disk corresponds to 1.333 Wh or 4800 Ws. Thus, at nominal power, there is one rotation approximately every 1.5 seconds and one pulse is output from the pick-up head. One of the 10 binary inputs can be used to monitor this, because they can be used for frequencies of up to 3 kHz and a minimum pulse width of 0.15 ms.

Because the pick-up head uses a connecting cable with a five-pole connector to connect to the CMLIB B, connect the pick-up head via CMLIB B (socket A) to counter input 1 (see Figure 1-2: "Test setup with meter (ML 266), reference meter (TVE 102/3) and CMC256 test set" on page 8).

The reference meter has a similar connection and is connected to counter input 2 via socket B. In this example, the reference meter must be connected via socket B of CMLIB B because the meter constant of the reference meter is 50 x 106 pulses / kWh which would exceed the capacity of the CMC 256. For the current input range of 0 ... 1 A at 220 V, this corresponds to a relatively high pulse rate of 9 kHz.

Only the RF counter input of the CMLIB B is able to read such a high pulse frequency correctly.

7

8OMICRON Test Universe1.3.2 Test SetupFigure 1-2:Test setup with meter (ML 266), reference meter (TVE 102/3) and CMC256 test set 1 2 3

1

4

2

5

3

6

4

7 8

0.. 20mA

9 10

0.. 10V

BIN ARY / ANALOG IN PUT

BIN ARY OUTPUTAUX DC AN ALOG DC IN PUT

1 2 3 NCURREN T OUTPUT B

1 2 3 4N NVOLTAGE OUTPUT

1 2 3 NCURREN T OUTPUT A

= 220V

B A

TVE 102/3Reference Meter

ML 266Meter to be tested

Ext. Interf.

Opticalpickup

SH 2003

CMLIB B

Meter1.3.3 Starting Meter in Stand-alone ModeStart Meter in stand-alone mode from the OMICRON Start Page by clicking M E T E R.

1.3.4 Setting up the Test ObjectTo configure the meter you are testing, use the Test Object software function. Open Test Object either by using the pull-down menu item P A R A M E T E R S | T E S T O B J E C T or by clicking the Test Object icon in the toolbar. In Test Object you can browse, access and edit the test object parameters.

A detailed description of Test Object and the closely related subject "XRIO" can be found in section 3 Setting Up the Test Object of the "Concept" manual.

1.3.5 Configuring the HardwareSelect P A R A M E T E R S | H A R D W A R E C O N F I G U R A T I O N and then click the Binary / Analog Inputs tab to define counter input 1 as a pulse input for "Wh exp." of the meter being tested.

Define the counter input 2 as a pulse input for the reference meter.9

1OMICRON Test Universe1.3.6 Defining the Test StepsSelect the Settings tab to specify the measurement conditions for the test.

Figure 1-3:Measurement settings

Values are:Defines the entries and readings as primary or secondary values.

Warm-up time:Defines the time period during which the nominal voltage is output to the voltage inputs of the meter.

This period allows the meter to reach its operating temperature prior to the beginning of the actual test. In particular for class 0.2 meters, an appropriate warm-up time is important, because the influence of the operating temperature on the meter error is the highest for such meters (for warm-up times see the manufacturer's description or DIN EN 61 036, 5/7, section 3.6.13).

Note: If the nominal voltage is manually switched on prior to the test (Test tab at Test View) and the test is then started, the warm-up time is ignored.0

MeterStart-up time:Defines the time that immediately follows the warm-up time without any interruption of the voltage. During the start-up time, the quantities defined for the subsequent test line are output. The meter starts to output pulses. The first pulse after the start-up time has elapsed is the initialization pulse (number 0) for the start of the test.

Ambient Temperature and Relative Humidity:

Define the values of the ambient temperature and the relative humidity. These values later appear in the test report.

The TVE 102/103 meter is used as the reference for the test. Select "Use Reference Meter" and click the N E W button to define the reference meter.

Figure 1-4:Defining a new reference meter

In this example, the reference meter has three different meter constants based on the current input range.

When you have finished defining the reference meter, click O K to return to the Settings tab.

Note: To make the settings of this reference meter available for other tests, save them to a text file (*.rmf). You can do this with the E X P O R T button in the Settings tab.

The settings of several meters can be saved together in one .rmf file. The data of the reference meter you have just defined are shown in Figure 1-5.11

1OMICRON Test UniverseFigure 1-5:Extraction from a .rmf file

This reference meter can now be used for future tests by importing this file.

Switch to the Test tab in order to define the test lines.

Step 1The error limits are verified (accuracy test). According to the PTB standard, the load points in Table 1-1 will be output for all measurement quantities.

Table 1-1:Three-phase four-wire system meter for active power consumption

Three-Phase Four-Wire System Meter for Active Power ConsumptionP(% of PN)

Load current (in % of In) cos Error limit (%)I1 I2 I3

0.05 0.05 0.05 0.05 1 0.50.1 0.1 0.1 0.1 1 0.50.05 0.2 0.2 0.2 0.25 1.00.067 0.2 0 0 1 0.60.067 0 0.2 0 1 0.60.067 0 0 0.2 1 0.60.25 0.5 0.5 0.5 0.5 0.51 1 1 1 1 0.52

MeterNote the following special items:

The input range 1A-L is used by the reference meter (0 ... 1 A) for test points 1 to 6 (0.25 to 1 A).

Therefore ensure that the reference meter is set to this range before the test starts.

The input range of the reference meter must be changed to 10A-L (0 ... 10 A) for test points 7 and 8 (2.5 and 5 A).

This has to be done manually between test line 6 and test line 7, while the test is running. To do this, select the "Pause test" check box in line 7 and define instructions for the tester. When running the test sequence, the test stops at the beginning of line 7 (the nominal voltage is output during the pause).

A dialog box appears showing the instructions for the tester (refer to Figure 1-6: "Define Trigger dialog box" on page 13). The test continues with line 7 after the input range of the reference meter has been changed and the "continue test" command has been issued.

Figure 1-6:Define Trigger dialog box13

1OMICRON Test UniverseAfter defining the 8 load points, the dialog box appears as in Figure 1-7.

Figure 1-7:Test View 1

Note: The Detail View, shown in Figure 1-8, is not needed to define symmetrical loads (test points 1-3, 7, 8). If the currents of the individual phases are different (test points 4-6), open the Detail View to enter the current values.

The permissible error limits depend on the particular load point and must be defined for every line individually in the "Tolerance" input field. The number of test runs should be 1 for all test lines.

Figure 1-8:Detail View4

MeterStep 2The next step is testing the creep behaviour, i.e., testing whether the meter starts or not. The "Creep" test mode must be selected and, according to the PTB standard, a load current of 0.005 x IN = 25 mA must be output at cos = 1. This test can be performed with either a single pulse as passed/failed criteria or the necessitiy of an additional pulse.

This test line is inserted into the test table as line 9 shown below.

Figure 1-9:Test View 2

The setting of the creep current is defined as a percentage of the nominal current. The default value is 1 %. Therefore the setting for a current of 25 mA is 0.5 %.

15

1OMICRON Test UniverseStep 3The no-load behaviour is tested. For this test, the "No-Load" test mode is selected, the voltage is set to 110 V (L-L) and the test time is set to 300 s. The current in all phases is 0 A and the voltage is between 80 % and 110 % of the nominal voltage (according to the PTB standard).

For this test to be assessed as "passed," the meter disk must not make a complete rotation. The standard does not specify the duration of the test period; so choose 5 minutes.

This test can be performed with either no pulse or max. one pulse as passed/failed criteria.

Note: The assessment of this test is rigorous. If the option "Accept one pulse in the no-load test" is not selected, and one pulse is registered, the meter is considered moving/started, and the assessment is negative ("test failed"). Depending on the position of the mark on the meter disk, even a very small movement of the meter disk can result in the registration of a pulse; e.g., if the mark was near to the pick-up head at the beginning of the test.

We recommend to select the option "Accept one pulse in the no-load test". This way Meter accepts exactly one pulse and still assesses the test as "passed".

Figure 1-10:Test View 3

Please note that now the test mode "No-Load" is selected, the voltage is set to

6

110 V (L-L) and the test time is set to 300 s.

MeterStep 4In the fourth and last step the counting mechanism is tested.

For this purpose 10 kWh at nominal load is output to the meter. The necessary time (3 hours, 1 minute and 50 seconds) is calculated by the software and displayed in the field "Nominal Time."

Note: At the beginning of this test line, a dialog box appears where you enter the meter reading at the beginning of the counting mechanism test. This dialog box appears again at the end of the test where you enter the meter reading at the end of the test. The error of the counting mechanism is calculated based on the entered values.

The complete test appears as in Figure 1-11.

Figure 1-11:Test View 4

The test can be started. The test lines in the table are performed beginning at test line 1. The results of each test line are entered into the table immediately after the test line is finished. 17

1OMICRON Test UniverseDuring the test run, the test status is displayed:

Figure 1-12:Test status during the test run

etc.

At the end of line 6 an information box appears prompting you to change the input range of the reference meter:8

MeterFigure 1-13:The test is paused

The test continues with line 7 after the input range has been changed and the C O N T I N U E button has been pressed. Line 11 (counting mechanism test) requires manual input as well.

Figure 1-14:Counting Mechanism Test dialog box

When the test is finished, the results are available for the report. 19

2OMICRON Test UniverseThe view in Figure 1-15 is displayed after the test is finished.

Figure 1-15:Test View 50

Meter1.3.7 Defining the Test ReportSelect P A R A M E T E R S | R E P O R T | R E P O R T S E T T I N G S and click D E F I N E . A dialog box appears where you can define the scope of the report.

Choose the "Condensed Report."

Figure 1-16:Defining the test report

The condensed test report appears as in Figure 1-17.

Figure 1-17:Condensed test report (extract)

The report can either be printed or exported to a file in RTF format (Rich Text Format). The file is later available for further processing with other programs (e.g., Word for Windows).21

2OMICRON Test Universe1.3.8 Saving the Test ReportThe results of the test, along with all of its settings (test object, hardware configuration, test module settings and test results) can be saved to be used again.

Select F I L E | S A V E A S . . . and enter a name for the test.

If you want to repeat the test later, re-load the document, delete the old test results, and then start the test.

This way tests can be repeated in exactly the same manner and error trends can be observed and recorded over a period of time.2

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MeterAbout MeterTime Sequence of a Meter TestMeter Example: Testing an Electromechanical MeterConsiderations Prior to the TestTest SetupStarting Meter in Stand-alone ModeSetting up the Test ObjectConfiguring the HardwareDefining the Test StepsDefining the Test ReportSaving the Test Report

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