R9MCT250 Schneider Resi9 Current Transformer Kit 250A Three Pieces PowerTag Meter CT Cabinet Set Unit

The R9MCT250 is the largest transformer in the Resi9 metering range, rated at 250 amperes with a 26.5 millimetre conductor opening and supplied in sets of three for three-phase circuits. It sits at the top of the universal meter's range, where the meter can be configured for 250 amperes and the transformer becomes the component that defines the accuracy of everything downstream.

Physically it measures 66 millimetres high, 60 millimetres wide and 29 millimetres deep — large enough that the layout inside the board has to be planned rather than improvised. Its 1.5 metre signal lead in a single pair provides enough length to route clear of busbars and protective devices.

At this current level, installation discipline matters more than the datasheet. The transformer has to close around a single conductor — in practice, the tails or the sub-main feeding a board rather than a bundled cable — and the 26.5 millimetre opening is what makes that possible for large-section cable.

The meter must be set to the 250 ampere configuration, because the universal unit derives its scaling from the transformer selection and a mismatch multiplies every reading by a fixed ratio.

The 250 ampere transformer is used on the incoming supply or a major sub-main, which is a different application from circuit-level metering. Typical uses include:

• Small commercial buildings — applied where the whole intake is to be measured and compared against the sum of the sub-meters, exposing unmetered loads and losses.
• Workshops, laundries and catering kitchens — specified where the installed load is genuinely heavy and the 160 ampere version would sit too close to saturation.
• Multi-let buildings — used by landlords on a shared intake where consumption has to be divided between tenants on a defensible basis.

In each case the same pattern applies: the 250 ampere set on the intake, 160 ampere sets on the sub-mains and 80 ampere sets on final circuits, all read by universal meters. This gives a metering hierarchy from one product family rather than three unrelated devices with three different interfaces.