15
Summing current measurement
When using two or more current transformers for
current measurement, the total transformer ratio
must be set at the UMG 510.
Example: Summing current transformer
Two current transformers are used for current meas-
urement. The ratios are 1000/5A and 200/5A respec-
tively. The outputs of these transformers are
summed by a summing current transformer with the
ratio 5+5/5A.
Use the setting for the UMG 510 as follows:
Primary current: 1000A+200A = 1200A
Secondary current: 5A
Current measurement
The UMG 510 is designed to be used with current
transformers. The nominal secondary current of the
CTs shall be 1A or 5A.
Each current measurement input stands 6A continu-
ously or 60A for 1 second.
If the system voltage is less than 150VAC to ground,
the current inputs can be used for direct measure-
ment of currents up to 5A.
Additional current instruments must be connected in
series with the UMG 510 inputs.
Fig. Example: Current measurement with external
amperemeter.
Installation
The secondary windings of the current trans-
formers must be short circuited at their termi-
nals before breaking the current measure-
ment circuit.
Fig. Example: current measurement using summing
current transformer.
