Df/Dt (Rocof) Monitoring (Option D) - Woodward MFR 11 Manual

Manual 37140A
df/dt (ROCOF) Monitoring
Function: "Rate Of Change Of Frequency (ROCOF) is not within permissible limits"
Rate of Change Of Frequency (ROCOF) monitoring measures the stability of the frequency. The frequency of a
generator will vary due to changing loads and compensation of the fuel system. The rate of these frequency
changes due to the load variances is relatively high compared to those of a large network. The control unit calcu-
lates the unit of measure per unit of time. The df/dt is measured over 4 sine waves to ensure that it is differenti-
ated from a phase shift. This results in a response time of approximately 100ms. This message can be suppressed
with the discrete input "Blocking of protective functions / remote acknowledgement".
df/dt-
Monitoring ON
df/dt
>
Response 0.0Hz/s
df/dt
Delay T= 0.0s
© Woodward
(Option D)
df/dt monitoring
ON................ Rate Of Change Of Frequency monitoring is enabled. The subse-
quent screens of this function are displayed.
OFF.............. Rate Of Change Of Frequency monitoring is disabled. The subse-
quent screens of this function are not displayed.
Tripping df/dt
The Rate Of Change Of Frequency threshold is defined by this parameter. If this
limit is reached or exceeded, the unit outputs the message "Fault df". If a relay
was assigned to this function in the relay manager, that relay will be energized.
Pickup delay
In order to initiate a Rate Of Change Of Frequency alarm, the measured df/dt must
exceed and remain above the configured threshold without interruption for at least
the period of time specified in this screen.
MFR 11 - Protection Relay
ON/OFF
1.0 to 9.9 Hz/s
0.1 to 9.9 s
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