Pos.Seq Reactive
Current Sec.
-300.00…
300.00A
0.01A Secondary measurement from each phase current channel reactive
current component.
I01 Resistive Current Pri.
-300.00…
300.00A
0.01A Secondary measurement from residual current channel I01 resistive
current component.
I01 Reactive Current Pri.
-300.00…
300.00A
0.01A Secondary measurement from residual current channel I01 reactive
current component.
I02 Resistive Current Pri.
-300.00…
300.00A
0.01A Secondary measurement from residual current channel I02 resistive
current component.
I02 Reactive Current Pri.
-300.00…
300.00A
0.01A Secondary measurement from residual current channel I02 reactive
current component.
5.2.2. Voltage measurement and scaling
Voltage measurement module (VT-module) is used for measuring the voltages from voltage
transformers and processing the measured voltages to measurement database and for use of
measurement- and protection functions (protection function availability depends on IED type). For the
measurements to be correct it is essential to understand the concept of the IEDs voltage
measurements.
Figure. 5.2.2. - 13. Voltage measurement terminology
For the measurements to be correct it is important to make sure that the measurement signals are
connected to correct inputs and direction of voltages are connected right and the scaling is set
correctly.
Relay calculates scaling factors based on the set VT primary and secondary voltage values. Relay
measures secondary voltages which in this case mean the voltage outputs from the voltage
transformer that is installed into the primary circuit of the application. Voltage can be measured up to
400V system directly as well. For the relay to “know” primary and per unit values the voltage
transformer rated primary and secondary voltages need to be set. In modern IEDs like the scaling
calculation is done internally after the voltage transformer primary and secondary voltages are given.
Normally the primary line to line voltage rating for voltage transformers between 400V and 600kV while
normally secondary voltage ratings are 100-120V. Non-standard ratings can also be directly connected
since the scaling settings are flexible in large ranges.
VT scaling example
The connection of VTs to the IED measurement inputs and the ratings of the voltage transformers are
as in following gure. In gure below line to neutral voltages are connected among with zero sequence
voltage. Other connection possibilities are presented in this chapter.
AQ-F255
Instruction manual
Version: 2.00
© Arcteq Relays Ltd
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