overheating or problems of instability due to overhauling of load.
c.
Provide controller fault protection so that a single or three
phase short circuit at the controller terminals or inverter
commutation failure will not result in damage to power circuit
components. Provide overload protection so that motor and
controller are protected against operating overloads.
d.
Provide adjustable time delay undervoltage protection so that
motors will continue to operate during momentary voltage
fluctuation or loss of voltage. Time adjustment shall be zero to
5 seconds. Provide for orderly shutdown on undervoltage
conditions exceeding the time delay interval.
e.
Provide adjustable timed linear acceleration and deceleration.
f.
Provide volts/Hz control to prevent motor overheating throughout
the speed range.
g.
Provide door interlocks to prevent opening of enclosure doors
unless power is disconnected.
h.
Controllers shall be self protecting and shall provide orderly
shutdown for, but not limited to, the following conditions:
(1)
Loss of input power
(2)
Undervoltage
(3)
Sustained gradual overload
(4)
Fault or large instantaneous overload
(5)
Overtemperature
(6)
Failure of ventilating system
(7)
Overvoltage
(8)
Control circuit failure
Provide contacts for remote annunciation of shutdown or abnormal condition.
i.
Electrical
Bypass: Provide each controller with manual isolation
and bypass
switching. Switch shall be manually operated with
controller
deenergized. Switch shall be two position with
provisions
for locking switch in either position.
(1) Normal Position: Bypass shall be open and controller shall
be connected to supply circuit and load.
(2) Bypass Position: Bypass shall be closed and controller shall
be electronically isolated from supply and load. Isolating
contacts shall be located so that it is possible to verify by
visual inspection that contacts are open and controller is
electrically isolated. In the bypass position the motor shall be
operated at constant speed and controlled from the air circuit
breaker. Provide auxiliary contacts that close in the bypass
position. Auxiliary contacts shall be used to activate the damper
SECTION 15501N
Page 131
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