Power Factor And Power Supervision - 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
52

Power Factor and Power Supervision

The power factor and the active power are important values to detect underload or no-load situations in applications where a
change of the load is not equally reflected in a change of the motor current (e.g. small pumps, conveyor belts etc.). For the supervi-
sion of the power factor a warning and a trip threshold is available. The power factor together with the motor current and the sup-
ply voltage are the basis to calculate the real power consumed by the motor. Warning and trip thresholds can be set both for over-
power and underpower supervision. The power factor and power supervision functions are disabled in test position and if a
voltage Dip was detected. An adjustable inhibit time is available to inhibit the load supervision functions after load start. This can
be used for example to allow a pump to built up pressure before the power protection becomes active. The diagram below shows
the startup of a motor and the activation of the underload protection function.
It is not necessary to specify the nominal power of the motor. The UMC100.3 internally calculates it as follows:
P = I
nom e
The warning and trip tresholds for the under - and overpower protection are therefore defined as percentage in re-
lation to Pn. Example: Pn = 2kW. If the parameter 'P Low Trip Level' is set to 80%' the motor will be tripped, if the
measured real power falls below 1.6kW.
Use either the cos phi or the active power for low load supervision. It is not recommendet to use both at the same
time.
I/I
n
100%
Motor start
Motor running
Load startup delay
—
The load startup delay time allows to delay the low-power protection functions at startup. This can be used for
example to allow a pump to built up pressure before the low power protection becomes active
√
∗ U ∗ cosϕ ∗
3
e nom
Power and
cosphi supervision
active
t