How are the wires connected to the ammeter on the field operation column?
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Current transformers are installed on the low-voltage switchgear circuits in the distribution room, along with a digital current meter. Now, a pointer-type ammeter needs to be installed on the motor’s local control panel. So, how should the wires of this ammeter be connected on the side of the low-voltage switchgear?
Just connect the current signals in series....
The ammeter is connected on the side of the low-voltage switchgear, via terminal blocks!
When connected in series, does choosing a secondary current of 1A or 5A for the current transformer have any impact on the operation panel? What should I be careful about?
When connected in series, does choosing a secondary current of 1A or 5A for the current transformer have any impact on the operation panel? What should I be careful about?
Just combine the two tables, right?
Parallel connection isn’t possible; the voltage transformer is used for measuring current in the main circuit, and the current in the main circuit equals the sum of the currents in the branch circuits. It can only be connected in series.
Then, the ammeter at the site must be connected using copper-wired cables that are run to a location away from the site; as a result, these wires will have resistance, and therefore the current reading will definitely be lower than that of the ammeter installed in the switchgear. And the readings shown are all around half of the circuit current; this error is way too large. Don’t deceive me – I’ve also studied physics in junior high school.
It means that the ammeter on the control column should have the same transformation ratio as that of the current transformer, right?