23
If the above conditions are met, the protection immediately exports 3J (C7/C8), 4J (C9/C10),
5J (C11/C12), and drives the accident signal relay 11J (C1/C3) (until manual reset, the relay will
not return), The accident light on the panel turns on. The logic block diagram of the action is
shown in 4-18 (high voltage system):
Switch closing
Over frequency protection--
ON
&
LCD display
Emergency signal outlet
Trip outlet
f Over frequency
Protection Value
Ua>5V
35HZ f<65HZ
T Over frequency
Protection delay
Figure 4-18: Logic diagram of over-frequency protection action
4.19 Low frequency load shedding
1
．
RLP20 Low frequency load shedding
－“
ON
”
；
2
．
Phase A voltage Ua>5V
（
High voltage system
）；
Phase A voltage Ua >50V
（
Low voltage
system
）
；
3
．
35HZ
≦
f <65HZ
；
4
．
The circuit breaker is closed, that is R1=1;
5
．
Protection device frequency f sampling value
≦
Low-frequency load shedding value
（
Fdz2
）
；
6
．
Duration of meeting the above conditions
≧
Low-frequency load shedding delay
（
Tfzd2
）
；
Meet the above conditions, the protection immediately exports 3J (C7/C8), 4J (C9/C10), 5J
(C11/C12), and drives the accident signal relay 11J (C1/C3) at the same time (the relay will not
return until manual reset), the panel The accident light is on. The logical block diagram of the
action is shown in 4-19:
Switch closing
Low frequency load
shedding--ON
&
LCD display
Emergency signal outlet
Trip outlet
f Low frequency load
shedding Value
Ua>5V
35HZ f<65HZ
T Low frequency load
shedding delay
Figure 4-19: Logic diagram of low-frequency load shedding protection action
4.20 Overvoltage
1
．
RLP21 Overvoltage
－“
ON
”
；
2
．
In line voltage Uab
、
Ubc
、
Uca
，
There are one or more sampled values
≧
Overvoltage value
（
Udz1
）
；
3
．
Duration of meeting the above conditions
≧
Overvoltage delay
（
Tuzd1
）
；
If the above conditions are met, the protection immediately drives outlets 3J (C7/C8), 4J