Generator Sensing

Single-phase generator sensing voltage is connected at TS3-E1 and TS3-E3. Three-phase generator

sensing is connected to TS3-E1. TS3-E2. and TS3-E3. The sensing inputs are applied to the primary of

sensing transformers T3 and T4. The output voltage from the transformer(s) secondary windings is rectified

and a representative sample, taken from a voltage divider network, is applied to the automatic voltage

regulator. Selection of single-phase or three-phase sensing is done with a jumper on TS2 (Refer to Section

3. Jumper Connections).

Automatic Voltage Regulator (AVR)

The AVR senses any change in generator output voltage and translates such changes into a dc error

voltage. When the auto / manual mode switch is auto, the dc voltage is sent to the firing circuits where it

modifies the gating pulse output originally established by the manual adjust control. When the AVR

determines that the generator output voltage is low, the gating pulses are applied to the power bridge SCRs

earlier in the cycle to cause a greater dc output. When the generator output voltage is high, the gating

pulses are applied later in the cycle causing less current in the generator field.