Woodward easYgen-3000XT Series, Руководство пользователя

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Fig. 196: Phase shift
A vector/phase shift as shown in ╚═▷ Fig. 196 causes a premature or delayed zero
passage. The determined cycle duration difference corresponds with the occurring phase
shift angle.
The monitoring may be carried out three-phased or one/three-phased. Different limits
may be configured for one-phase and three-phase monitoring. The vector/phase shift
monitor can also be used as an additional method to decouple from the mains. Vector/
phase shift monitoring is only enabled after the monitored voltage exceeds 50% of the PT
secondary rated voltage.
Function "Voltage cycle duration not within the permissible range"
The voltage cycle duration exceeds the configured limit value for the phase/vector shift.
The result is, that the power circuit breaker that disconnects from the mains, is opened,
the message "Mains phase shift" is displayed, and the logical command variable "07.14"
is enabled.
The prerequisite for phase/vector shift monitoring is that the generator is operating in a
mains parallel operation (the MCB and GCB are both closed).
df/dt (ROCOF)
df/dt (rate of change of frequency) monitoring measures the stability of the frequency.
The frequency of a source will vary due to changing loads and other effects. The rate of
these frequency changes due to the load variances is relatively high compared to those of
a large network.
Function "Rate of change of frequency not within permissible limits"
The control unit calculates the unit of measure per unit of time. The df/dt is measured
over 4 sine waves to ensure that it is differentiated from a phase shift. This results in a
minimum response time of approximately 100 ms (at 50 Hz).
ID Parameter CL Setting range
[Default]
Description
3058 Change of frequency 2 Off Monitoring is disabled.
[Phase shift] Phase shift monitoring is carried
out according to the parameters
described in
╚═▷ “Phase shift” .
524 easYgen-3000XT Series B37574
4 Configuration
4.5.3.12 Change Of Frequency
Released