Technology of Electrical Automatic

Why meter show negative current?

Most of Blue Jay metering device support four-quadrant energy parameter measurement, that mean current signal access meter must distinguish vector direction of the current flow.


For example: 194 series Multifunction Power Meter, once cabled and connected is seen to give a correct voltage and current reading, but shows negative values for active power (generation). This is an error with the cabling for the current transformer secondary;


The direction of the transformer current has to be respected as shown in the connection diagram. The current transformers have a two face for primary side cable or busbar, the current must pass from P1 to P2 giving the result in secondary (S1 and S2) of 5 amps.

The error stems from:

a). The current transformers have been incorrectly installed. As a result, it gives the direction of the current as passing from P2 to P1; to resolve this problem, the current transformer does not have to be dismantled and installed again, but the transformer secondary (S1 and S2) just has to be inverted.

b). The connection of the current secondary in the current transformers have been incorrectly connected; to resolve this problem just connect the S1 transformer secondary to the S1 on the meter and the S2 on the current transformer to the S2 on the meter.