Table of Contents
Advertisement
SMC-3™ SMART MOTOR CONTROLLERS
Description of Features
Electronic Motor Overload Protection
The SMC-3 controller incorporates, as standard, electronic motor overload protection. This motor overload
protection is accomplished electronically with the use of current transformers on each of the three phases.
The controller's overload protection is programmable, providing the user with flexibility. The overload trip
class selection consists of either OFF, 10, 15, or 20. The trip current is easily selected by adjusting the
rotary potentiometer to the motor full load current rating. Trip reset is selectable to either automatic or
manual mode.
Note:Trip rating is 120% of dial setting.
Over-temperature
The SMC-3 monitors the SCR temperature by means of internal thermistors. When the power poles maximum
rated temperature is reached, the microcomputer switches off the SMC, a TEMP fault is indicated via LED,
and the 97/98 fault contact closes.
Phase Reversal Protection
When enabled via a DIP switch, 3-phase input power will be verified before starting. If input power phasing
is detected to be incorrect, the start will be aborted and a fault indicated.
Phase Loss/Open Load
The unit will not attempt a start if there is a single-phase condition on the line. This protects from motor
burnout during single-phase starting.
Phase Imbalance
The unit monitors for imbalance between phase currents. To prevent motor damage, the unit will trip if the
phase imbalance exceeds 50% current imbalance for 3 seconds, and a fault will be indicated.
Shorted SCR
Prior to every start and during starting, the unit will check all SCRs for shorts and unit load connections to
the motor. If there is a shorted SCR in the SMC-3 and/or open load, the start will be aborted and a shorted
SCR or open load fault will be indicated. This prevents damage from phase imbalance.
Push to Test
The unit with control wiring can be tested for fault conditions by using the Push to Test function. Hold down
the Reset button for 5 seconds to activate the fault Aux (97, 98) and shut down the SMC-3. To clear, either
push the Reset button or cycle control power to the device.
35
Advertisement
Table of Contents
