PSI Technologies have many years experience in the Rail Industry and were well placed to respond to London Underground’s request for their new rail electrical contactors.  Contactors galvanically isolate the electrical drive train from the power supply when it is switched off, with an auxiliary contact reducing coil current after the contactor closes.  The requirement was to optimise the de-energising response time, because if switching off takes place under load, an electric arc can be generated in the contactor, which is hard to extinguish.

The solution lay in the rugged 200 series MAC valve utilising Viton, an increased strength return spring, and gold electrical pins, both of which prevent ARC and premature system failure through ensuring a precise and reliable opening of the electrical connectors.   This is an example of a traditional MAC valve, with the unique features* which are the very hallmark of a MAC valve, being  modified to apply to a very modern situation.

The 200 series is a direct solenoid operated 3-way poppet valve, with a Hazardous Location version.  It features a short stroke solenoid, a balanced poppet and powerful return spring.  These features mean high shifting forces, fast consistent response times and long life.