Battery contactor for electric forklifts

High-performance forklifts have to quickly and safely transport loads weighing several tons to the maximum lift height. In addition, they should be emission-free and quiet.
That increasingly makes electric forklifts the first choice. But it increases the requirements, too. In particular, this applies to simultaneous travelling and lifting, and emergency stops. Electric industrial trucks operate at the usual voltage levels in conjunction with currents up to max. 300 A.

Reliable disconnection in emergencies

Three-phase motors (drive motor and lift motor) controlled by an inverter are installed in modern industrial trucks. The control mechanism within the inverter is assumed by semiconductors.

If the semiconductor has a technical problem, it can no longer be switched off in the worst case scenario. The current simply continues flowing and the vehicle would continue moving, for example, even if the driver wanted to stop; or a load would continue to be lifted even though a barrier is in the way.

By actuating the emergency-stop switch, the contactor which is controlled by the central electronics drops out. The entire vehicle is isolated from the power supply and thus removed from danger. The contactor ultimately represents the fall-back level on the DC side for a non-functioning inverter.

What do the Schaltbau C110B contactors do?

• In normal operation: As a main contactor in industrial trucks, it connects the battery and drive unit and, if required, it can disconnect the connection securely: both in normal operation (battery discharge) and during the charging process.
• Emergency disconnection: The contactor disconnects the entire vehicle from the power supply and induces a safe state.
• In the event of service: In service mode and during maintenance, there are various test steps to be performed in which the contactor must switch.
• Factory holidays or lengthy downtimes: The contactor disconnects the battery pack from the vehicle drive. Therefore, battery discharge from silent consumers (standby currents of control units), for example, can be prevented.

Why DC contactors C110B series are used here:

• Cost-optimised contact system: adjusted material usage (e.g. with silver and copper), optimised for target service life
• Sealed design: Dust and dirt cannot enter (IP 40)
• Double break contact through bridge contact
• Contact system is designed for the new service life requirements of electric industrial trucks