Power measurement including differential current measurement
- The voltage is measured via connections L1, L2, L3 and N.
- The current is measured using three or four current transformers (e.g. from the Beckhoff SCT series) via the connections IL1, IL1‘, IL2, IL2‘, IL3, IL3‘ as well as IN and IN‘.
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WARNING: Risk of injury through electric shock! Bring the bus terminal system into a safe, de-energized state before starting mounting, disassembly or wiring of the bus terminals! |
Fig.180: Usual wiring of the EL3453 power measurement terminalIn the following illustration, the current measurement channel IN is used to measure the neutral conductor current.
Fig.181: Usual transformer arrangement for the EL3453 power measurement terminal including neutral conductor measurementIllustration of another transformer arrangement for direct measurement of the differential current:
Fig.182: Transformer arrangement of the EL3453 for differential current measurement with transformer (red) of the SCT4xxx seriesThe secondary current path of the differential current transformer must be connected to the IN (and IN') terminal contacts.
To calculate the differential current value correctly, the corresponding transformer ratio must be entered in CoE object 0xF804:12.
Example: Transformer ratio 1A:50A corresponds to a value of 0.02 to be entered.