Operation Manual 37107F
MFR 3 - Multi Function Relay
© Woodward
Page 71/165
Mains Current, CT / Mains Power
Mains current measuring via mains current transformer/CT
Parameter
30
Current transf.
mains 0000/x
CT ratio, mains
5 to 7,000/x A
The current transformer ratio is necessary in order to display the actual values and
control the power. When sizing a CT for the system, the minimum current flow for
the CT should not be lower than 60% of the transformer's rated current at rated cur-
rent. A lower percentage may lead to malfunctions and additional inaccuracies in
the control and monitoring functions also occur.
The primary rated current of the CT must be entered here. It is indicated on the data
plate of the CT. The secondary rated current cannot be configured and is 5 A
If the current in the primary winding of the CT reaches the primary rated current,
the secondary rated current flows in the secondary winding of the CT.
Example for current transformer ratio 300/5:
Current in the primary winding = 300 A -> current in the secondary winding = 5 A
Current in the primary winding = 150 A -> current in the second. winding = 2,5 A
Parameter
31
Angle adjustment
Mainscurr. 000°
Angle adjustment for measuring of mains current
-180 to 180 °
If a transformer is located between the measuring point for the voltage of the mains
and the generator, it is possible that there is a phase shift between these two mea-
suring points. If so, special voltage transducers must be used to adjust the phase
angle of the voltages. The synchronization is at the right phase angle with these
transducers, but measurement of the mains power is wrong because mains current
is still measured without phase angle correction. This configuration screen allows
the user to adjust the phase angle measurement of the mains current, so that the
measurement of the mains power is correct.