How Neutral Current (Current N or I4) is calculated or measured in PM8000?

Issue
How Neutral Current (Current N or I4) is calculated or measured in PM8000?
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Product Line
PM8000 series meters
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Environment
Power Monitoring Expert (PME)
ION Setup
Modbus mastering
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Solution
As stated in PM8000 Modbus Register Map, there is a Register named: Current N with Modbus Register 3006 which is also named as I4.

When PM8000 meter is setup with volts mode 4W-WYE, I4 Modbus Register will display a value for the current value when:
A: I4+ and I4- terminals are wired as 3CT Wiring with specific wiring of -(I1+I2+I3). Refer to Image 1.
or
B: I4+ and I4- terminals are wired as 4CT Wiring. Refer to Image 2.

Image1:


Image 2:


Note: Under both above wiring connections, the value of I4 on the meter is affected by the I4 CT ratio.

If there is no current through I4 terminal, then I4 register will return zero. Refer to Image 3.

Image 3



The PM8000 has another register, I5 at Modbus register 3008, with label Current G. This current is the residual current -(I1+I2+I3+I4). When meter wired as shown in image 1, I5 will always be zero.

Released for:Schneider Electric India