Power factor capacitors discharged safely

. Capacitors in domestic electronic equipment can give a nasty shock if they are touched without discharging them first, retaining about 0.7J of energy. Jim Wallace, product and technology manager of Seaward Electronic, says a bank attached to a wind turbine can store 420J. To meet the need for a safe, packaged solution to this problem, Seaward has developed the SD300, a unit that can be attached to capacitor banks of up to 1200 microFarad at voltages up to 1kV, discharge them safely, and indicate when this has been accomplished through the use of analogue meters on each phase and LEDs. Two-hand, push-button operation to initiate and maintain energy discharge ensures that the operator cannot come into contact with the live circuit. Other safety features include an automatic pre-use self test, protection against prolonged connection to live operating circuits, and monitoring of critical component temperatures with automatic cut off. Once activated, stored energy is discharged in 30s or less. Wallace said: “The project has been driven by one particular manufacturer of wind turbines.”