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The “PASS” or “FAIL” message is generated using the PT accuracy class (see Section 13.9.1

)

and the selected error limit from the User Preferences menu. If no PT nameplates are selected in

the Site Editor, the PowerMaster

estimates a nameplate according to the readings and a default

accuracy class of 0.3. Once the measured ratio is displayed, the PowerMaster

calculates the

error to see if it is within limits. For example, if the measured ratio is 3.76:1, the nameplate is 4:1,

the accuracy class is 0.1, and the error limit is set to “2.0x Specification Accuracy,” then the

PowerMaster

will display a “FAIL” message. Here is how it is calculated:

[(3.76-4) / 4]*100 = -6.0% error

(Accuracy class = 0.1) * (Error limit = 2) = ±0.2%

6.0% > 0.2% = FAIL

Testing Tips:

1. Verify the probe is rated for the voltage being tested. Only use probes meeting the

manufacturer’s specifications. Using probes that do not meet the manufacturer’s

specifications may lead to a safety hazard.

2. Never connect a voltage probe around a conductor before terminating it to its cable and to

the PowerMaster

3. For Litewire probes, verify the optic cable is clean to prevent surface arcing.

4. Position the probe as far as practical from other voltage carrying conductors.

5. IN GENERAL, if a PT Ratio test has an erroneous ratio result or a phase angle greater

than ±1°, check the installation of the voltage probe before suspecting a PT problem.

Using the Volt Litewire Probe

PowerMaster

Connections:

1. Connect the 3-Phase Probe Adapter Cable to either SET 1 or SET 2.

2. Connect the HV Signal Cable (stamped with the Volt Litewire serial number) to the red

connector on the 3-Phase Probe Adapter Cable.

Connection to the Service:

Refer to the Volt LiteWire manual provided on page 7 (“Making Phase to Ground

Measurements”). Please note that when doing phase to ground measurements, using a “hot tap

clamp” is simply referring to any clamp device (i.e. vice grips) to tie the Phasing Electrode to earth

ground (refer to page 14 of the Volt Litewire manual for a picture of the Phasing Electrode).

The user also has the option to view phase to phase measurements (see page 9 for “Making

Phase to Phase Measurements With two Hot Sticks”). These measurements can be viewed and

saved in any hot screen. However, performing a PT Ratio Test can only be done with phase to

ground measurements.

Rev 1.5 106

PowerMetrix PowerMaster 3 Series User Manual

Questions and Answers: