Installation manual

GEO Direct PWM Amplifiers – Preliminary Documentation
22 System Wiring
Regen (Shunt) Resistor Wiring
The Geo Drive family offers compatible regen resistors as optional equipment. The regen resistor is used
as a shunt regulator to dump excess power during demanding deceleration profiles. The GAR48 and
GAR78 resistors are designed to dump the excess bus energy very quickly.
The regen circuit is also known as a shunt regulator. Its purpose is to dump power fed back into the drive
from a motor acting as a generator. Excessive energy can be dumped via an external load resistor. The
GEO product series is designed for operation with external shunt resistors of 48 Ω for the 10 and 15 amp
versions or 78 Ω for the 1.5, 3, and 5 amp versions. These are available directly from Delta Tau as
GAR48 and GAR78, respectively. These resistors are provided with pre-terminated cables that plug into
connector J5.
Each resistor is the lowest ohm rating for its compatible drive and is limited for use to 200 watts RMS.
There are times the regen design might be analyzed to determine if an external Regen resistor is required
or what its ratings can be. The following data is provided for such purpose.
Caution
The black wires are for the thermostat and the white wires are for the regen resistor
on the external regen resistor (pictured above). These resistors can get very hot. It
is recommended that they be mounted away from other devices and near the top of
the cabinet.
The regen resistors incorporate a thermal overload protection device available through the two black leads
exiting the resistor. It is important that these two leads be wired in a safety circuit that stops the system
from operating should the thermostat open.