Is it mandatory to use a contactor with a voltage relay?

Cyril asks:
Hello! I read your articles on the voltage relay, where it says that at powers above 7 kW you need to put a contactor. But found on the manufacturer's website DIGITOP V-protector 63A (13.8 kW). I called them. They say that it can protect the entire apartment without a contactor. Initially, I thought to break the protection into 3 groups (3 separate relays), but they say that when a single relay is triggered, everything will turn off. Are they right and which values ​​to choose? Thanks in advance, Cyril.
The answer to the question:
Hello, Cyril! Where is it written? What article is it written in? Can you give an example? Perhaps there is a mistake or you misunderstood the essence of what was said. A lot of relays on 63A, that is, they are designed for direct connection to the network with a total power of up to 13.8 kW. A contactor is needed if the relay is designed for less current than it is necessary to protect.

On this occasion: "... when one relay is triggered, everything will turn off." In the sense? If the relays are parallel and protect their groups, then they will operate exactly at the voltage that you set. If you set the same limits everywhere, everything will turn off. If in one of the groups, for example, lighting, you set the voltage range to 160-250 volts, and for the rest, let's say 180-240, then when the voltage jumps to 245 volts, or drops to 170 volts, for example, then all the equipment will turn off and then the lighting will work until the voltage rises above the set 250 volts or drops below 160 volts. Thus, you can set different voltages at which the equipment will turn off.

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