Profile: Castell offers safety interlocking systems. We provide well-engineered solutions to safety problems. We are ISO 9000 certified. We offer products like mechanical switch gear, electrical switch interlocks, solenoid control switch and key exchange units. The FS interlock is designed for use as a mechanical interlock for electrical switch gear. Solenoid controlled trapped key interlock switch is designed to control access to hazardous machines with a rundown time.