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DC contactor
Use 2-pole or 3-pole contactor
DC contactor



DC contactor
2-pole or 3-pole contactor wired for DC loads
DC direct current is different than AC alternating current.

AC current oscillates back and forth on the wire each time generator rotates 50-60 times per second. US and Americas the standard is 60 cycles. Europe Asia Africa etc 50 cycles. With AC electricity, the electrons actually change direction. At the midpoint in each oscillation, the voltage crosses zero volts, making it easier to extinguish the arc caused by disconnection of a switch.
DC current does not oscillate. Instead, the electrons flow through circuit at same direction and voltage at all times.
When AC voltage hits zero volts, then the arc or spark or heat is easy to extinguish.
Result: AC switchgear, like contactors, last million of repetitions without melting the points.
High voltage DC is different. When high voltage DC is turned off, the electrons keep pushing because the voltage never reaches zero.
Result: DC voltage causes arc or spark or heat that is difficult to stop. Basically the electrons keep piling up and pushing the arc across the points of the contactor.
DC switchgear must be rated for DC voltages, and be capable of extinguishing DC arc.
Illustration shows one method of extinguishing DC arc using 3-pole contactor. The circuit has 3 parallel switches on the positive wire, thus helping to stop the arc better than 1 switch
With a 4-pole contactor, 3 poles can be used to turn off Positive, and 1 pole to turn off Negative.
To help eliminate arcs, add a resistor in parallel with inductive winding. Example of inductive winding is motor load

Buy:
3-pole contactors
120Volt coil
40 amp 240Volt coil
24 volt coil
Packard contactor
Mars 2-pole and 3-pole contactors
Rheem HVAC replacement contactors
50 amp contactor
60 amp contactor

Resources:
Solar contactor/ pdf
DC relays for solar
DC contactor wiring diagrams/ pdf
What is 3-phase electricity
Can AC circuit breaker be used for DC
DC to DC relay   DC power relay
250VDC    25 amp                        400VDC  200 amp

250 volt / 25 amp DC load

DC power relays with 12-24 VDC coil

Full on-off contacts/ 12 or 24 volt DC coil
250 volt / 25 amp DC load
250V x 25 amp = 6250 watt
Connect 12 or 24 volt DC to terminals 3-4; 
Connect load to terminals 1-2

Buy:
24 VDC coil 250VDC electromechanical DC-DC G9EB-1 relay
G9EB-1-B-DC24
24 VDC coil and 400 VDC/ 200 amp contacts
Omron relay at online
Fuseholder

Resources:
Omron-DC-DC-relay-Datasheet
Omron DC-DC pdf
DC power relay spec sheet

12 VDC  40-50 amp DC power relay

Buy:
Magnecraft box and cover
magnecraft w199 relays at Amazon
Siemens power relays at Amazon

Resources:
Magnecraft relay / pdf


Use AC contactor instead:
3-pole 
When 1st pole burns out, move wires to 2nd pole, etc
Siemens 3RT10/ 460 volt AC 5 Hp/ 24VDC coil
3-pole 90 amp contactor/ 120 volt coil
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