Allen-Bradley SMC-50, User Manual

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28 Rockwell Automation Publication 1560F-UM001A-EN-P - June 2019
Chapter 1 Product Overview
Voltage Unbalance Protection
The SMC-50 module is able to detect an unbalance in line voltages. Motor
operation can be halted if the unbalance is greater than the desired range.
The SMC-50 module provides an adjustable unbalance setting from 1…25% of
the line voltages. Trip delay time can be adjusted from 0…99 seconds.
An alarm (pre-fault) indication level can be programmed to indicate the unit is
getting close to faulting. The alarm modification information is displayed
through the HIM, Communication (if applicable), and alarm contact closing.
Current Imbalance
A current imbalance condition can be caused by an unbalance in the voltage
supply, unequal motor winding impedance, or long and varying wire lengths.
When a current imbalance condition exists, the motor can experience an
additional temperature rise, which results in degradation of the motor insulation
and reduction in life expectancy. Rapid current imbalance fault detection helps to
extend the motor’s life expectancy and minimize potential damage and loss of
production.
The current imbalance calculation is equal to the largest deviation of the three
current signals (RMS phase current) from the average phase current, divided by
the average phase current. Note that the power pole current is used for the current
imbalance calculation.
Current imbalance setting is adjustable from1…25% of the phase current. Trip
delay time can be adjusted from 0…99 seconds. This protection is also available
when motor is at speed.
Stall Protection and Jam Detection
The SMC-50 control module provides both stall protection and jam detection
for enhanced motor and system protection.
• Stall protection is user-adjustable from 0.0…10.0 seconds (This feature is
enabled by Default and delay time set at 1 s).
• An alarm (pre-fault) indication level can be programmed to indicate the
unit is getting close to faulting. The alarm modification information is
displayed through the HIM, Communication (if applicable), and alarm
contact closing.
• Jam detection allows the user to determine the jam level (up to 1000% of
the motor’s full-load current rating) and the delay time (up to 99.0 s) for
application flexibility.