This Guide will introduce negative current in Blue Jay metering device, including what is negative current and why the meter shows a negative current.
What is the negative current in the metering device?
In an electric meter, negative current usually means that the current is flowing in the opposite direction to the meter connection. Electric meters are used to measure the magnitude and direction of electrical current and are usually designed to display only positive current values. When the direction of the current flow is opposite to that of the meter connection, the meter may display a negative current value. This does not mean that the current itself is negative, it just means that the current is flowing in the opposite direction to what the meter indicates.
Why meter show a negative current?
Most Blue Jay metering devices support four-quadrant energy parameter measurement, which means the current signal access meter must distinguish the vector direction of the current flow.
For example: the 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 the 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 of negative current 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 has 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.