Usage:
Remote Voltage Control
Partial View Of Regulator
(1) Potentiometer. (2) Jumper. (3) Regulator.
Generator output voltage level can be controlled from a remote location. This is done by connecting potentiometer (1) between terminals (6 and 7) on voltage regulator (3).
Remove jumper (2) between terminals (4 and 7) for remote voltage level control.
For acceptable voltage control, the remote mounted potentiometer must be 10k ohms ± 5% with three turns and a dielectric strength of 1000 VAC minimum.
The terminals of the remote mounted potentiometer are fragile. The wiring connected to remote mounted potentiometer (1) should not have a diameter larger than 18 gauge. Larger diameter wire is not recommended. The wire should be 600 volt class with a 90°C (194°F) insulation.
NOTE: Either jumper (2) or remote potentiometer (1) is required for regulator operation.
Series Boost
Series Boost Schematic With Earlier One Fuse VR3
Series Boost Schematic With Current Two Fuse VR3
Series boost lets self-excited SR4 generators stay on the line, for approximately 10 seconds, when there is a short in the generating or load circuits. This gives circuit breakers a chance to trip in sequence. When circuit breakers trip in sequence, there is less chance for a loss of power to all of the electrical system.
Series boost consists of the series boost module and current transformer T2.
Reference: For the most current information on connecting to the primary side of the transformer, see Special Instructions, SELS0071.
Voltage sensing and power are applied to the series boost module from the voltage sensing terminals 22 and 24 of the regulator.
When the sensed voltage is within normal limits, an electrical signal is sent to the gate of a triac located in the series boost module. This triac short circuits the current transformer T2. This prevents any series boost during normal operation.
If there is a short circuit that causes the voltage at the regulator sensing terminals to drop to a low value, the control signal to the gate of the triac will be turned off. Current from current transformer T2 will be rectified and applied directly to exciter stator L1. This field current will be enough to give at least three times full load current into a short circuit. After approximately ten seconds a timer within the series boost module will again cause a control signal to be applied to the gate of the triac. The triac will short circuit the current transformer T2. Current flow to exciter stator L1 will be zero until the short circuit is corrected.
Manual Voltage Control
Manual Voltage Control Schematic With Earlier One Fuse VR3
Manual Voltage Control Schematic With Current Two Fuse VR3
Manual Voltage Control Panel
(1) Switch (OFF, AUTO and MAN positions). (2) Voltage control rheostat. (3) Fuse.
The manual voltage control can be used to control generator voltage when there is a failure in the generator regulator assembly. It will manually control the current flow to exciter stator L1.
The manual voltage control panel has switch (1) and voltage control rheostat (2) for the manual operating mode.
Switch (1) is used to make the selection between AUTO, MAN and OFF. In the "AUTO" position, the VR3 regulator controls the generator voltage. In the "OFF" position, the voltage will go to zero. In the "MAN" position, generator voltage is controlled by voltage control rheostat (2) on the manual voltage control panel.
NOTE: The Manual Voltage Control Panel must not be installed in a location that is subject to engine vibrations or directly to outside weather.
NOTE: When the manual voltage control is operating in the "Manual" mode, it is not necessary for the VR3 regulator to be connected to the generator. However, the manual control must remain connected to generator sensing lines No. 20 and No. 24.
Voltage Droop Transformer And Adjustment Rheostat For Parallel Operation
Generator And Regulator Schematic
(1) Voltage droop transformer. (2) Voltage droop rheostat. (3) Lead. (4) Main stator.
Operation of generators in parallel requires voltage droop as reactive load is increased. Droop transformer (1) and adjustment rheostat (2) are required to provide the voltage droop function. The transformer senses load current in lead (3) of main stator (4). Droop rheostat (2) provides adjustment of droop voltage. Rheostat (2) is located directly next to the regulator on the regulator mounting bracket.
Transformer (1) and rheostat (2) are standard on some generators and an attachment on others.
NOTE: Droop transformer (1) must be installed on generator phase lead T8, for 10/12 lead generators with transformer polarity connections as shown.
NOTE: Droop Transformer (1) is a special ratio transformer.
Single Phase Sensing
Connection Diagram For Single Phase Sensing
(1) VR3 regulator. (2) Jumper. (3) Main stator. (4) Exciter stator.
VR3 regulator (1) can be reconnected for single phase voltage sensing. This is used for special operations such as operating single phase loads with an open delta stator connection.
One sensing lead is disconnected [lead 22 in the illustration]. Then jumper (2) must be provided between terminals 20 and 28 on the voltage regulator.