The XP3509 module has been designed in conjunction with RailCorp as a diode blocking circuit required for the electromagnet clutch control in GEC Point Machines (Type H.W 4400 Single Phase A.C). The module also provides surge protection for the A.C input and LED fault indication. LEDs are illuminated when the point machine is powered in forward or reverse direction. No indication means either diodes or surge protection is damaged. Features include compact design, easy to use and highly reliable.