Woodward HighPROtec MCDLV4, Руководство пользователя

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Protective Elements
Voltage vector surge.
As shown in the voltage/time diagram the instantaneous value of the voltage jumps to another value and the phase
position changes. This is called phase or vector surge.
The relay measures the cycle duration. A new measuring is started at each zero passage. The measured cycle
duration is internally compared with a reference time and from this the deviation of the cycle duration of the voltage
signal is ascertained. In case of a vector surge as shown in the above graphic, the zero passage occurs either
earlier or later. The established deviation of the cycle duration is in compliance with the vector surge angle.
If the vector surge angle exceeds the set value, the relay trips immediately.
Tripping of the vector surge is blocked in case of loss of one or more phases of the measuring
voltage.
Working Principle delta phi
(Please refer to the block diagram on next page)
The frequency element supervises the three voltages (depending on if the voltage transformers are wired in Star or
Delta connection »
VL12«, »VL23« und »VL31« oder »VL1«, »VL2« und »VL3«).
If any of the three phase voltages is e.g. below 15% Vn, the vector surge calculation is blocked (settable via
parameter »
V Block f«). According to the frequency supervision mode set in the Device Planning (delta phi), the
phase voltages are compared to the set vector surge threshold.
If, depending on the parameter setting, in all three,
in two or in one of the phases, the vector surge exceeds the set threshold and if there are no blocking commands
for the frequency element, an alarm and a trip command is issued instantaneously.
861 MCDLV4 DOK-HB-MCDLV4-2E
V(t)
V(t) V(t)`
Trip
t
t=0
delta phi
Voltage Vector Surge