ION9000 VT wiring and meter config Question

[EE103]

I am looking for confirmation that the ION9000 is correctly wired and configured for voltage readings with the below configuration. The system in question is a 3-phase, 3-wire system with a neutral bond via low resistance ground. The phase-to-phase voltage is 34.5kV and the VT ratio is 34500:120. With the below configuration, ION setup gives the warning "PT Primary/nominal mismatch."

Metering Setup - Basic
PM1 Volts Mode: 4W-WYE

PM1 PT Prim: 34500.0
PM1 PT Sec: 120.0
Nominal Voltage: 19918.58

[Mehran_Mehrnia]

Hi @EE103 

Nominal Voltage refers to the primary power system RMS voltage (line-to-line voltage for Delta
systems and line-to-neutral voltage for Wye systems).

In Wye system as shown in the image above, the PT primary and secondary are referenced to the Neutral, therefore, the PT primary is considered as VL-N which is supposed to be 19918.58(34500/√3).
The Nominal voltage is 19918.58 while the PT primary is entered as VL-L which is 34500.

Best Regards,

-Mehran

L3 Expert Advanced metering

[Charles_Murison]

Hello @EE103 ,

A lot will depend on what the outputs of the VT are. Is the VLL output on the secondary side 120V Line to time, or 120V Line to Neutral? Depending on the answer to this you may have different options.

If VT output is 120 V Line-to-line, then options include ignoring the warning, there is nothing wrong with your settings. Just not a common way to configure a meter, which is why ION Setup is giving a warning. Another option is to change the PT settings. PT Ratio is 287.5 (34500/120), have PT Primary =19838, PT Secondary =  69. This way the nominal voltage is close to the setting in PT Primary.

If VT output is 120V Line-to-Neutral, then may need to check your PT primary setting as I think there is likely a mistake.

If you read meter's voltage values for Line-to-Line or Line-to-Neutral, do you see your expected values?

Regards,

Charles

[EE103]

Thanks for the info Charles & Mehran.

The VT output is 120V line-to-line (Measuring with a multimeter between V1 & V2 gives 120V, measuring between V1 and VN gives ~69V) and I do get the expected values for Vab and Van in the meter with these settings. It sounds like the settings are correct, I am fine ignoring the warning so for the sake of accuracy I will leave the PT primary and secondary values as-is.

As a follow-up question, I would like to ensure that my configuration for generating COMTRADE files for voltage sag/swells. The goal would be to trigger a waveform capture and COMTRADE file generation when voltage exceeds +/- 5% of nominal (>36225V & <32775V) and reset the trigger at +/-3% of nominal (>35535V & <33465V). The current configuration is below, and with these settings it appears that the meter is currently in an active sag/swell state although the voltages are within the limits described above.

Alarming - Sag/Swell - Voltage
Enabled Selected

Nominal: 19918.58 Volts

Swell Limit: 105%
Sag Limit: 95%
Hysteresis: 2%
Alarm Priority: Info Only

Power Quality - Sag/Swell Logging
Data Logging: 100 Records
Waveform Logging: 30 captures @ 32x54, 7 pre-cycles

COMTRADE: 10

[Charles_Murison · Accepted solution]

Hello @EE103 ,

When meter is in 4Wire Wye volts mode, the sag swell module will read the voltage RMS from the Line-to-Neutral voltage terminals by default. There is a setup register in the sag/swell module to use VLL always, this would force the module to ONLY use line to line voltages.

Regards,

Charles 

[Robert_Lee]

At present ION Setup will generate the warning if the entered V Nominal is outside of plus/minus 10% of the PT Primary setting so given that the PT primary setting is 34500 and the nominal is under 20000, that would be why its generating the warning.