ABB UMC100-FBP - Page 45

- 45 - UMC100-FBP
Universal Motor Controller
UMC100-FBP
Technical Description
FieldBusPlug / Issue: 03.2012
Phase Loss Protection (Current)
This function protects motors against the extreme situation where a complete phase is lost. An unde-
tected phase loss can cause motor damage because of the sudden rise of current in the two remaining
phases. Thus the thermal overload protection performs an accelerated trip during phase loss. This func-
tion is based on the motor current and detects a phase loss while the motor is running.
The phase loss protection function must not be disabled in real applications. The phase loss
protection may only be disabled for demo purposes.
To the detect a phase loss the current in the remaining phases must be > 25% of I
e
.
The following table shows the tripping times in case of phase loss for the different trip classes.
Trip class 5 10 20 30 40
Tripping time [s] 1.5 3 6 9 12
Relevant Parameters:
•Phase Loss Protection
Phase Imbalance Protection (Current)
Imbalance protection function protects the motor against a small degree of imbalance in the motor
phases e.g. caused by an increased contact resistance due to corrosion.
The current phase imbalance function signals a warning when the current in a phase differs more than the
configured warning level from the average current in all 3 phases. A fix hysteresis is built in.
The current phase imbalance protection signals a fault when the current in a phase differs more than the
configured trip level from the average current in all 3 phases for a period of time. This time is trip class
dependant and shown in the table above.
Block Diagram:
I123
Imb >
Warning Level
Imbalance
Warning
After Start-up
&
Imbalance
Trip
Imbalance
Detection
Imb >
Trip Level
During Start-up
>1
&
 Signal flow of the phase loss (current) protection function.
Relevant Parameters:
•Curr Imb Trip Level •Curr Imb Warn Level