LXi-2900 Wye Delta Open Transition
Hubbell Fire Pump Motor Controllers with Automatic Transfer Switches (ATS) are
designed to comply with the latest standard of the National Fire
Protection Association for the installation and operation of centrifugal
Fire Pumps (NFPA-20).
Model
LXi-2900 is a combined automatic and manual wye-delta reduced current fire
pump controllers applied where the capacity of the power source does not
permit across-the-line starting of the motor. The controllers are used
with special six (6) or twelve (12) lead squirrel cage motors designed
for wye-delta starting.
The motor is
started connected in wye, drawing approximately 33% of the locked rotor
current and producing approx. 33% of its locked rotor torque. After a
short time delay, the controller transitions the motor to the delta
connection. The motor current & torque jump to the across-the-line
current & torque at the speed at which the transition takes place.
The current quickly falls to its normal running current as the motor
accelerates to full speed.
The difference in
the LXi-2800 and LXi-2900 is the transition between the wye and delta
connections. The LXi-2900 has open transition between the wye and delta
connections. This condition can cause current surges or disturbances
back into the power source and can affect the operation of other
equipment.
The LXi-2800 has
closed transition between the wye and delta connections through the use
of an additional contactor and resistor. The LXi-2800 provides a smoother
transition by keeping power on the motor during the transition.
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