33
Power
Select the display of the active power of the
three phases. Assuming that there is no gen-
erator operation, positive active powers of
a similar size should be displayed for each
phase. If not, the current transformers are
probably reversed or assigned to the wrong
phase.
Check the total power outputs
If all voltages, currents and outputs for the
respective outer conductors are correctly
displayed, the total power outputs measured
by the UMG507 must also be correct. To
confirm this, the total outputs measured by
the UMG507 should be compared with the
work of the active and reactive power meters
located in the incoming supply.
Check the individual powers
If a current transformer has been assigned to
the wrong outer conductor, the correspond-
ing power will be incorrectly measured and
displayed.
The assignment of the outer conductor to the
current transformer at the UMG507 is correct
if there is no voltage between the outer con-
ductor and the corresponding current trans-
former (primary).
In order to ensure that an outer conductor at
the voltage measurement input is assigned to
the correct current transformer, the respective
current transformer can be short-circuited on
the secondary side. The apparent power dis-
played by the UMG507 must then be approx.
zero in this phase.
If the apparent power is correctly displayed
but the active power is displayed with a „-“
sign then the current transformer terminals
are reversed or power is supplied to the power
supply company.
Checking the Measured Values
L1
L2
L3
kW
kW
kW
Current
Switch to the currents display. The read off
balues should agree with the currents actually
flowing. If not, check the wiring and the cur-
rency transformer setting.
Check the current direction
Short-circuit two current transformers on the
secondary side. The active power displayed
in the remaining phase of the UMG507 must
now be positive (+) for drawing of active power
and negative (-) for supply (generator opera-
tion) of active power.
If no active power is displayed the assignment
of the voltages to the currents may be wrong.
