1 AC contactor in an emergency can substitute DC contactor, pick-up time cannot exceed 2 hours (because the AC coil heat dissipation than DC difference, this is decided by their different structure), really want to use for a long time the best series resistance in AC coil, in turn, but turns in the coil can not substitute for DC AC contactor

 2 AC contactor less, DC contactor coil turn number, from the size of the coil can distinguish the condition of too large for the main circuit current (Ie>250A) under the condition of using the double winding coil contactor coil in series

3 DC relay the reactance is large, small current. If the AC adapter is not damaged, when the right time to put. But the coil of AC relay reactance is small, current is big, if connected to DC will damage the coil.

 4 AC contactor has the short circuit ring on the core, DC contactor shall be free from the principle of