Contactor
Definition
An electrically controlled switch designed to handle high DC voltages and currents in battery systems. Contactors provide the main disconnect mechanism for isolating the battery pack from the load.
Why It Matters
- Primary safety device for emergency shutdown and isolation
- Must be rated for DC voltage and interrupt rating of the battery system
- Failure modes include welding closed (dangerous) or failing to close (operational failure)
- Proper sizing prevents contact welding during normal operation
Common Pitfalls
- Undersizing continuous current rating leads to contact degradation
- Using AC-rated contactors for DC applications (different arc behavior)
- Not implementing auxiliary contacts for state verification
- Ignoring coil power consumption in system energy budget