GE MiCOM P142 Agile User Manual

V00854
System Frequency
Holding Band
Restoration
Frequency
Shedding
Frequency
Underfrequency
Element
Holding
Timer
Restoration
Timer
Stage 1 Restore Start
Stage 1 Restore Enable
Trip
Off
Complete
Off
Off
Off
Off
On
On
Complete
Underfrequency
Element Pick -up
Underfrequency Trip
Stage (n) Load
Shedding
System Frequency
Recovery Starts
Restoration Time Starts
System Frequency Partial
Decay Restoration Timer
Suspended
System Frequency
Recovery Continues
Restoration Timer
Resumes Timing
Restoration Time
Completes Stage
(n) Load
Restoration
Time
Time less than
Holding Timer Setting
Figure 134: Load restoration with short deviation into holding band
If the system frequency remains in the holding band for too long it is likely that other system frequency problems
are occurring and it would be prudent to reset the restoration timer for that stage. For this reason, as soon as the
system frequency is measured to be within the holding band, the "Holding Timer" is initiated. If the system
frequency doesn’t leave the holding band before the holding timer setting has been exceeded, the load restoration
time delay for that stage is immediately reset.
Note:
The holding timer has a common setting for all stages of load restoration.
An example of the case when the time in the holding band is excessive is shown below.
Chapter 11 - Frequency Protection Functions P14x
252 P14xEd1-TM-EN-1

GE MiCOM P142 Agile Specifications

General

Brand	GE
Model	MiCOM P142 Agile
Category	Control Unit
Language	English