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DC contactor |
Use 2-pole or 3-pole 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 |
  250VDC 25 amp 400VDC 200 amp |
250 volt / 25 amp DC loadDC 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 |
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12 VDC 40-50 amp DC power relayBuy:Magnecraft box and cover magnecraft w199 relays at Amazon Siemens power relays at Amazon Resources: Magnecraft relay / pdf 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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