Overexcitation Time Delay

If the regulator output voltage exceeds 65 Vdc ±2 Vdc, the

regulator automatically makes a connection across

terminals A1 and A2 via an optically-isolated triac device.

This occurs after a time delay which is inversely

proportional to the magnitude of the regulator output

overvoltage condition up to approximately 105 Vdc ±5 Vdc

(see Figure 2). Beyond this point, the field voltage is

removed at a much faster rate. To avoid tripping due to

the voltage provided by a separate current boost circuit,

voltage measurement excludes any additional boost

voltage term. The overexcitation circuit is reset by

reducing the regulator input voltage to less than its buildup

value for 5 seconds.

This feature is designed to protect the generator and

regulator by allowing disconnection of the overloaded

part(s) of the system. Should the regulator be allowed to

run in excess of its rated current for any extended period

of time after the protection output closes, failure of the

recommended supply fuse will occur, but regulator

damage may also take place.