57
UMG 806
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11.4 Measured current
The device:
·Measures current exclusively via current trans-
formers.
·Is designed for the connection of current trans-
formers with secondary currents of ../1 A and ../5
A.
·Does not measure DC currents.
The factory-set current transformer ratio is 5/5 A
and must be adapted to the current transformers
used as needed.
The current transformers require a basic insulation
according to IEC 61010-1:2010 for the nominal
voltage of the circuit.
1. Short-circuit all current transformer outputs
except one.
2. Compare the current displayed on the device
with the applied input current.
- The currents must match after taking the
current transformer ratio into account (see
section “Basic parameter settings”).
- In the short-circuited current measurement
inputs, the device must indicate approx. 0
amperes.
11.5 Checking the phase assignment
The assignment of the phase conductor to the cur-
rent transformer is correct if a current transformer
is short-circuited on the secondary side and the
current indicated by the device in the associated
phase conductor drops to 0 A.
11.6 Checking the power measurement
1. Short-circuit all current transformer outputs
except one and check the indicated powers.
2. The device must only display power in the
phase conductor with the current transformer
output that is not short-circuited.
3. If this is not the case, check the connections
of the measured voltage and the measured
current.
If the amount of the measured active power is
correct, but the sign is negative, this can have 2
causes:
1. Reversed connections S1(k) and S2(l) at current
transformer or
2. Active energy is being delivered back into the
grid.
11.7 Checking measurement
Correctly connected voltage and current measure-
ment inputs result in correctly calculated and dis-
played individual and summation power readings.
11.8 Checking individual power
If a current transformer is assigned to the wrong
phase, the corresponding power is measured and
displayed incorrectly.
The phase conductor and current transformer are
correctly assigned on the device if there is no volt-
age between the phase conductor and the associ-
ated current transformer (primary).
To ensure that a phase conductor at the voltage
measurement input is assigned to the correct cur-
rent transformer for the power measurement, the
respective current transformer can be short-cir-
cuited on the secondary side. The apparent power
displayed by the device must then be zero in this
phase conductor.
If the apparent power is displayed correctly but
the active power has a negative (“-”) sign, then
the current transformer terminals are reversed or
power is being supplied to the electric utility.
11.9 Checking summation power
If all voltages, currents and powers for the respec-
tive phase conductors are correctly displayed, the
summation powers measured by the device are
also correct. To confirm, compare the summation
power values measured by the device with the
power values of the meters installed in the feeders.
Summary of Contents for UMG 806
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