A hermetically sealed 200 A DC contactor rated to 750 V, for switching a traction circuit. This is main contactor duty: the part that connects and disconnects the pack itself.
Switching 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 750 V will keep burning across separating contacts until something puts it out. An ordinary relay in this position welds shut, 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.
Hermetically sealed means the contacts live in a controlled atmosphere that quenches the arc as they part, and that no moisture, dust or gas ever reaches them. That is what lets a device this size interrupt this much current, and why its performance does not drift over the years.
The coil is polarity sensitive. It accepts anything from 9 to 36 V, which is generous, but it has to be connected the right way round. Reverse it and the contactor will not pull in, and in some conditions the coil can be damaged.
Key specifications
| Manufacturer part | Durakool DEVR20 |
|---|---|
| Type | Hermetically sealed DC contactor |
| Continuous current | 200 A |
| Rated voltage | Up to 750 V DC |
| Coil voltage | 9 V to 36 V DC |
| Coil polarity | Sensitive, must be correct |
| Contact chamber | Hermetically sealed, with arc suppression |
| Weight | 0.48 kg |
Features
- 200 A continuous, which is main traction contactor duty rather than auxiliary switching
- Hermetically sealed contacts with arc suppression, so it can interrupt DC at 750 V
- Wide 9 to 36 V coil range, so it suits both 12 V and 24 V vehicle systems
- Sealed against moisture, dust and gases for its whole service life
- Long mechanical and electrical life under load
Compatibility
For EV traction packs, battery management systems and industrial DC power control up to 750 V.
Observe the coil polarity. It is stated on the contactor and it matters.
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, which is what a precharge circuit exists to prevent. Use a precharge resistor and a contactor controller.
In the box
- 1 x 200 A DC contactor
Downloads
The Durakool datasheet is in the Documents tab, with the contact arrangement, coil data and derating curves.



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