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Control Circuit_neutral/ 024VDC switching
Neutral/ 024VDC switching in control circuits.

Hello there,

Recently I inspected a control panel. I noticed that all the relays and contactors for 230VAC was controlled with neutral instead of phase and the DC circuit (contactors and relays) was controlled with negative 24VDC.

This was the second time I'm experiencing this control logic and was difficult to find out the fault. Why the contactors and relays are controlled with neutral or negative supply instead of phase or +24VDC?