Tornatech GPU, Installation And Maintenance Manual, Page: 6 / 67

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MODEL GPV: ACCELERATION RESISTOR STARTER
This model does not require a multi-connection motor. It only requires 3 conductors between the controller
and the motor.
Upon a start command, a set of acceleration resistors in each phase is utilized to supply a reduced voltage
to the motor. After a time delay, the resistors are shunted out and the motor is connected to full voltage by a
closed transition switching sequence.
MODEL GPW: WYE-DELTA CLOSED TRANSITION STARTER
This model requires a multi-connection motor and 6 conductors between the controller and the motor.
Upon a start command, the motor is connected to the line in the wye connection. After a time delay, the
motor is reconnected to the line in the Delta configuration applying full voltage to the motor windings by a
closed transition switching sequence.
The power source does not « see » any open circuit during the transition from wye to delta. During the
transition from Wye to Delta, a resistor bank is connected in the starting circuit and allows to keep the motor
coils energized. An 80 second delay is then triggered and prevent the motor from stoping. This delay allows
the resistors to cool down and will only be triggered if the transition occur. An emergency stop can still be
perform by pulling the disconnecting mean handle.
MODEL GPY: WYE-DELTA OPEN TRANSITION STARTER
This type of starter requires a multi-connection motor and 6 conductors between the controller and the
motor.
Upon a start command, the motor is connected to the line in the Wye connection. After a time delay, the
motor is reconnected to the line in the Delta configuration applying full voltage to the motor windings. This
controller is of the open transition type. The motor is disconnected from the line during the transition from
start (wye) to run (delta) mode.
Types of Automatic Transfer Switch
TRANSFER SWITCH CATALOG NUMBER
MODEL No. EXAMPLE: GPA+GPU - 480 / 20 / 3 / 60
Model Prefix GPA+GPU
Voltage 480 V
HP Rating 20 HP
Phase 3
Frequency 60 Hz
Methods of Starting/Stopping
The controllers are available as combination automatic / non-automatic with provision for manual or automatic
shutdown (an automatic shutdown is only possible after an automatic start).
METHODS OF STARTING
AUTOMATIC START
The controller will start automatically on low pressure detection by the pressure sensor when the pressure drops
below the cut-in threshold.
MANUAL START
The motor can be started by pressing the START push button, regardless of the system pressure.
REMOTE MANUAL START
The motor can be started from a remote location by momentarily closing a contact of a manual push button.
REMOTE AUTOMATIC START, DELUGE VALVE START
The motor can be started from a remote location by momentarily opening a contact connected to an automatic
device.