How to connect a voltage relay with a contactor?

Vladimir asks:
Good afternoon!

I am collecting ASU for a summer residence. There are 3 phases for input, 380 V, 15 kW. Single-phase consumers are distributed evenly in phases, and a three-phase consumer is one - saw 3 kW in a tree. I want to protect myself from, already taking place, a zero break. To solve the problem, I quickly bought a three-phase voltage relay ABB 1SVR730885R3300, CM-MPS.21S, believing that it is three-phase on both sides. And having already bought it, I realized that I needed a contactor. Do I understand correctly that the contactor must have at least three NC contacts and be connected through two NC contacts of the voltage relay, there are few such on sale. So far, only one contactor has found that meets this requirement: DEKraft Schneider Elektric MK-103, 4 NC, 40 A, 230 V. Please tell me, is my train of thought correct?

The answer to the question:
Good afternoon. I did not understand everything that you wrote. Most of the sold contactors are three-phase, that is, they already have three power contacts, these are those that are NZ. Plus at least 1 block contact (also NC). And you sent the most common three-phase contactor. And how to understand "through two NC contacts of the voltage relay"? The voltage relay should break the power supply circuit of the contactor coil, so it will turn off the power in the house.

Your relay has two pairs of switching contacts that switch from a closed state to another closed state (to another contact, in simple terms). You just need to buy a contactor and connect one of the contacts closed during normal power supply to the coil gap.

For example, if a 220V coil (as on the contactor that you sent) can be connected as follows:

phase - contact 15; pin 18 - coil; the second output from the coil is zero.

If the coil is 380, instead of zero, connect another phase.

I hope I clearly explained and did not make a mistake in the logic of the relay. The point is that those contacts that are closed in the state when the relay is in operation, that is, the voltage in the network is good, the contacts are closed, judging by the diagram from the catalog - in the normal (de-energized) position, 15-16 and 25-26 are closed, and 15 -18 and 25-28 are open. when the voltage is normal, as I understand it, 15-18, 25-28 are closed.

In practice, it can be the other way around (I did not find normal technical information, the graphs from the instructions are generally incomprehensible and without explanation) that you will have to connect to the gap not 15-18, but 15-16, if they are closed with good voltage and all phases .

How were you going to connect? Tear two RELAY contacts and phase and zero to the coil? Well, you can, but not necessarily!

I hope I clearly stated the idea and you thought in the right direction! How to connect, unsubscribe to any contacts you connected, please.

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