reduced at start-up, the starting torque is reduce d as well. The object is to r edu ce the starting
voltage to just the volt age necessary to develop th e torque required to get th e motor moving.
The voltage and cu rrent are then ra mped up in a desir ed period of ti me. The voltage is reduced
through the use of silicon c ontrolled rectif iers (SCR). Onc e full voltage is reached, a bypass
contactor is energi z ed t o bypass the SCRs.
There are a number of LEDs (li ght -emitting diodes) t hat are useful in troublesh ooting and
starter checkout on Be ns ha w, Inc. solid-state s ta rters. These are used to in dicate:
voltage to the SCRs
SCR control voltage
power indication
proper phasing for rotation
start circuit energized
• overtemperature
ground fault
When voltage is supplied to the solid-state circuitry, the heat sinks within the
starter are at line vol t ag e. Do not touch the heat si nk s while voltage is prese nt o r
serious injury will result.
WARNING !WARNING