Operation Details For Motors With Small Set Currents - ABB UMC100.3 Manual

U M C 1 0 0 . 3 U N I V E R S A L M O T O R C O N T R O L L E R T E C H N I C A L D E S C R I P T I O N
26
If current transformers of other suppliers are used the table above may serve as a calculation basis for the current
factor.
Example: Type CT5L500R/4 means: Primary 500 A, secondary 4 A, current factor 125.
In the UMC the real motor current has to be set e. g. 500 A.
For high efficiency motors the start-up current can be > 8 * I
In this case it might be necessary to use the next larger CT if the startup-current is above
the max. current listed in the table above.
Examples:
• I = 180 A, startup-current 7*I
e
• I = 180 A, startup-current 10*I
e

Operation Details for Motors with Small Set Currents

When using a UMC100.3 in an environment with very strong magnetic fields and a small set current at the same time,
the current measurement can deviate a few percent from the real current. Therefore the displayed motor current is
too high and an overload trip occurs too early.
Very strong magnetic fields can originate from a contactor directly mounted beside the UMC100.3, closely passing
current links or stray fields caused by large transformers.
When observing the effect, the distance between the UMC100.3 and the contactor shall be increased to about 5 cm
or the UMC100.3 turned by 90 degrees or the motor wires shall be looped through the UMC100.3 two to five times.
When looping the motor wires multiple times, the parameter Current Factor must be adjusted according the number
of loops. I.e. the parameter must be set to two if the wires are looped through the UMC100.3 two times. Two to five
loops are supported. The displayed current and the current transmitted over the fieldbus are automatically correc-
ted by the UMC100.3.
Please note that the adaptation of the current factor for √3 circuits and multiple loops through the UMC100.3 are
not possible at the same time.
Via fieldbus also higher values than five e. g. six can be set.
The UMC100.3 ignores such values and creates a parameter fault. Values above 100 are
possible and used in combination with external current transformers (see previous page).
Related parameters:
• Current Factor
• Nominal current 1 / 2
-> 1260 A -> Use CT4L185R/4
e
-> 1800 A -> Use CT4L310R/4 in this case.
e
.
e