ION Regular Power meter values - calculation method?

[conradvr_hexeis]

In the ION power quality meters ION7650, ION7400, PM8000 and ION9000 the regular Power Meter module updates the outputs once per second.

Are the output values of this module the mean of all cycles within the 1 second interval or the RMS value of the last cycle within the 1 second interval?  For example in a 50Hz system is the Phase A current the:

1. Mean of the last 50 cycles OR

2. The snapshot value of the last cycle

We have an application that needs to calculate and record the 1 second mean per phase currents in ION7650 and ION9000 devices.

[Charles_Murison · Accepted solution]

Hello @conradvr_hexeis ,

In the power meter module, the current and voltage value is the RMS over the entire 1 second interval.

Regards,

Charles

[DanL]

Hello Conrad,

Can you please describe or elaborate on the use case for the mean of the rms of previous 50 cycles of current?

I presume you you did not imply that the desired 1s value was the arithmetic mean of all instantaneous current (because this tends to 0A on all transformer coupled meters)?

As Charles indicates, the one second power meter module computes the RMS (aka. quadratic mean) of all cycles each second for voltage and current. The active and reactive power quantities are the (linear) arithmetic mean of power over 1 second.

Dan

[conradvr_hexeis]

Thanks David and Charles.  We needed to confirm that this was the RMS value over all cycles over the 1 second interval and not just the RMS value of the last cycle in the 1 second interval.

Correct I did not imply that this was the arithmetic mean of instant current values.

The use case is we are needing to plot a client's actual load at the 1 second point on a Time Rated Load Period Curve.

When using the high speed Power Meter module are the RMS values calculated on the last power cycle?

[Charles_Murison]

Hello @conradvr_hexeis ,

The High speed Module is RMS for a full cycle updated every 1/2 cycle.

Charles