1) What is the structural difference between the DC and AC contactors in addition to the coil?
2) What are the problem if the AC power and voltage connect the coil at the rated voltage of the coil when the voltage and current are similar?
Answer to Question 1:
The coil of the DC contactor is relatively tall and thin, while the AC contactor coil is short and fat.Therefore, the coil resistance of the DC coil is large, and the coil resistance of the AC coil is small.
DC contactors and DC relays often use a double coil, where the current coil is used for suction and the voltage coil is used for suction hold.
The AC contactor is a single coil.
The iron core and armature of the DC contactor are the whole electrical soft iron, and the AC contactor is the silicon steel sheet stack to reduce the AC loss.
The flux in the AC contactor core is alternating and has over zero.At this time, the armature will bounce back under the reaction force, and then hold after zero, so the AC contact core needs to be equipped with a short circuit loop to eliminate the magnetic through zero oscillation.
contactors and relay coils produce overvoltage upon release, DC contactors and relays are generally eliminated with reverse diodes, and AC contactors and relays with RC circuits.
DC contactor contact arc difficult, to match magnetic blow arc.AC contactor is relatively easy to arc, using C-shaped structure and arc gate.
Answer to Question 2:
The DC contactor coil current is small when the DC voltage is the AC effective voltage.Therefore, when the two power supplies are switched, the DC contactor is likely not engaged, and the AC contactor burns immediately.
In addition, the DC contactor immediately burns after the supporting continuation diode on the AC circuit.
Post time: Feb-07-2023
