The Low Power Current Sensor (LPCS) can be used to replace conventional current transformers (CTs) and is particularly useful for normal CTs or full load current (FLCs) ratings between 10 to 200Amps. The CT has been designed to IEC61869-10 in order to provide a true 5p10 rated protection class current transformer in a small package size.
The output of the sensor is 840mV making it compatible with the previous P&B Hall Effect Sensor (HES) which provides 3-phase current measurement to the relay. It is often used for high-density tiers starters where the physical fitment of a conventional iron core ring type CT is simply to large for the starter cubicle or tray.
Here, the LPCS benefits from a large pass through aperture to accommodate the primary conductor.
Where a relay specification would be normally MV2-1A, the secondary CT rating of the product description is replaced with HES to indicate connection to this type of sensor, i.e. MV2-HES, so a MV2-HES can now be connected to a LPCS.
A LPCS is chosen in the same way as a conventional CT, where the rating is typically rounded up to a figure somewhat higher than the FLC of the motor, as a rule of thumb the FLC is in the region 50-100% of the CT.
The LPCS is connected to the relay via a 1metre 10 way ribbon lead allowing the LPCS to be installed in close proximity to the primary circuit connections (or at the rear of the withdrawable starter tray) and the relay, which is door mounted to be installed within the low voltage (LV) compartment (or at the front of the withdrawable starter tray).
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