GE 750, Instruction Manual

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13-
22
750/760 Feeder Management Relay GE Power Management
13.5 ANALOG INPUT 13 S6 MONITORING
13
13.5.4 ANALOG INPUT RATE OF CHANGE
The relay has fast and slow analog input rates of change. The fast rate of change measures over the last one
minute interval and detects a rapid increase or decrease in the input quantity. The slow rate of change mea-
sures over the last one hour interval and detects the long term trend of the input quantity. A positive rate indi-
cates an increasing analog input and a negative rate indicates a decreasing analog input.
The fast (slow) analog input rate of change is calculated as follows. Every second (minute) the present analog
input reading is captured and a new rate of change calculated for the previous minute (hour). The rate is calcu-
lated using the previous sixty analog input readings and the ‘Least Squares Approximation’ method that gener-
ates an equation for the best line through the sample points as shown below. The rate of change is equal to the
slope of this line which is a stable quantity not unduly affected by noise or fluctuations from the input.
Figure 13–11: ANALOG INPUT RATE OF CHANGE MEASUREMENT
The following setpoints are also repeated for
ANALOG IN RATE 2
.
■
ANALOG IN RATE 1
■
[ENTER] for more
The
ANALOG IN RATE 1
setpoints path is:
\ SETPOINTS \ S6 MONITORING \ ANALOG INPUT \ ANALOG IN RATE 1
ANALOG IN RATE 1
FUNCTION: Disabled
Range: Disabled, Alarm, Latched Alarm, Control
Select the required function. Note that a connected analog input will still be
read and displayed in
A2 METERING \ ANALOG INPUT
if both the analog threshold
1 and analog threshold 2 functions are set to ‘Disabled’.
ANALOG IN RATE 1
RELAYS (3-7): -----
Range: Any Combination of the 3-7 AUXILIARY Relays
Select the output relays required.
A.I. RATE 1 PICKUP:
10.0
µ
A /hour
Range: –1000.0 to 1000.0 in steps of 0.1
Enter the pickup value for this analog in rate monitoring element. When the
measured value of analog in rate exceeds this setting for a period longer than
the programmed delay, an alarm will occur and the user-selected relays will
signal an output.
ANALOG IN RATE 1
DELAY: 0 s
Range: 0 to 60000 in steps of 1 s
Select the delay required.
5.5
6
6.5
7
7.5
0 5 10 15 20 25 30 35 40 45 50 55 60
Time (seconds)
ANALOG
INPUT
(mA)
ANALOG INPUT
ANALOG INPUT RATE