APPNOTE: Connecting a PM7000 or PM7000FLM using VTs and CTs

Article ID: 211008KE
Last Reviewed: October 8th, 2021

The information in this article applies to:

  • Users connectiong a PM7000, PM7000FLM and a PM4000 to Secondary VTs and CTs

Target Audience.

This article is aimed at:

Summary.

A summary of the points to note when measuring from secondary VTs and CTs using a PM7000, PM7000FLM or a PM4000.

Article.

If measuring either Power Quality or the Fault Level at HV there must be appropriate secondary current and voltage transformers available at the measurement sites to which the unit can be connected.  Clamp on CTs with various ratios (0-1A and 0-100A (switchable) and 0-10A CTs) are available depending on the output ratio of the secondary CTs.  The voltage measured directly by the unit can be up to 600V.

The CTs will have to be specified per site according to the secondary CT output level. The relevant ratios will then need to be input into the unit user interface PMScreen using an Android Tablet, Mobile Phone or Windows PC .

Rogowski coils (6000A) provided with the unit can be used if measuring at LV.

It is worth noting that if running off measurement VTs and CTs the burden of the PM7000FLM when powering off the voltage being measured is normally <10 VA from Phase A. However, powering the unit off a grounded 12VDC charger will see the burden drop to 16.2MOhms per differential input, although if not grounded it will be 32MOhms.