400 A / 750 V DC Contactor With Integrated Economiser
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A 400 A DC contactor with an integrated economiser and a 9 to 36 V coil. Main traction contactor duty: the part that connects and disconnects the pack itself.
Breaking DC at pack voltage is the hard problem this part solves. Alternating current crosses zero a hundred times a second and any arc drawn on opening extinguishes itself. Direct current never does, so an arc struck at several hundred volts keeps burning across separating contacts until something puts it out. An ordinary relay in this position welds, and a welded main contactor means a pack that can no longer isolate itself, which is the worst failure a high voltage system can have.
The integrated economiser is the feature worth paying for. A contactor needs a strong pull to close and only a fraction of that to stay closed. Without an economiser it draws the full pull in current for as long as it is energised, which on a vehicle means hours: that is wasted energy from the 12 V system and it is heat inside the contactor. An economiser drops the coil to a holding level automatically once it has closed, so the coil runs cool and the 12 V load stays small. Better still, it is built in, so there is nothing external to design or get wrong.
The 9 to 36 V coil range means it works from both 12 V and 24 V vehicle systems, and it tolerates the voltage sag that comes with cranking or heavy 12 V loads.
Key specifications
| Part | 400ACONTACTOR |
|---|---|
| Type | DC contactor with integrated economiser |
| Continuous current | 400 A |
| Coil voltage | 9 V to 36 V DC |
| Coil control | Integrated economiser, automatic hold reduction |
| Weight | 0.5 kg |
Features
- 400 A continuous, which is full traction contactor duty
- Integrated economiser, so coil power and coil heat drop automatically after closing
- Wide 9 to 36 V coil range, suiting 12 V and 24 V systems and tolerating sag
- No external economiser circuit to design, build or get wrong
Compatibility
For EV traction packs, battery energy storage and industrial DC power control.
Check the voltage rating against your pack before ordering. The product name and the description on this listing give different figures, so please ask us to confirm the rated voltage for the unit in stock rather than working from either. The datasheet in the Documents tab is the authority.
Do not close it onto an empty DC link. A main contactor closed directly onto an inverter's capacitance draws an inrush that welds the tips. Use a precharge resistor and a contactor controller.
In the box
- 1 x 400 A DC contactor
Downloads
The manufacturer datasheet and a 3D CAD model in STEP format are in the Documents tab. The datasheet is the definitive source for the voltage rating.
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