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Transformer protection


9521 transformer protection relay

9521 transformer protection relay

9521 Transformer protection measuring and control device is mainly used to 35KV、20KV、10KV and below level voltage transformer of protection measuring and control,The protection device has perfect protection function and communication function,widely used in various requirements of the municipal projects and power plant projects!If you need more powerful, high requirement products, you can choose the 972 high-end transformer protection devices.
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Protection function:

01. protection for current instantaneous trip               (tripping)

02.protection for time delay  current instantaneous trip          (tripping)

03. Protection for Over current                (tripping) 

04. protection for Inverse time over-current       (General / very / extreme)

05. Protection for Over load          (Alarm / trip)

06. protection for Zero sequence time delay  current instantaneous trip ent instantaneous trip   (tripping)

07. protection for Zero sequence time delay  current instantaneous trip   (tripping)

08.protection for Zero-Sequence definite time over-current .     (tripping)

09.Protection for Zero-Sequence Inverse time Over current (General / very/ extreme)

10.Protection for Zero-Sequence Over-Current     (Alarm / trip)

11protection for over  voltage (tripping)

12.Protection for low voltage (tripping)

13.protection for under-frequency load shedding    (Trip)

14. PT line-break (give an alarm)

15. protection for PT no-voltage (give an alarm)

16. The main changes to open the door   (Alarm / trip)

17. Negative control trip (tripping operation)

18. heavy Buchholtz (tripping operation)

19. light Buchholtz (give an alarm)

20. Temperature is too high (tripping operation)

21. Temperature rise (give an alarm) 

22. loss of close circuit and trip circuit (give an alarm)

Description: in the conditions, the protection function can be increased to meet the needs of the field.


Remote control function:

01.Measuring current:IA、IC(sampling value*N2),Ia、Ic( sampling value);

   02. Bus voltage:UAB、UBC、UCA(sampling value*N2),Uab、Ucb( sampling value);

03. Zero sequence time delay  current instantaneous trip ent:i0( sampling value);

04. power:P、Q(sampling value*N2);

05. power factor:cos Ф;

Control function:

01. The local closing and local tripping of circuit breaker 

02. The remote closing and remote tripping  of circuit breaker

Auxiliary function:

01. Operation instruction:When the device is running normally,“on”Indicator light flashes regularly;

02. Power instruction:When the device is running normally,“on” indicator light is always on;

03. Device Abnormally :checksum error-default,blocking relay output;

04. Device alarm:Current, the voltage reaches the set value and remains to the set time,Alarm and collect on-off input;

05. Device trip:Current, the voltage reaches the set trip value and remains to the set time.

06.on/off instruction:on/off instruction of switch status;

07. Event record:Can record 32 protection events, 32 remote events, 8 self test events;

08. Online modification:“device in service and out of service”and“Protection fixed value” can be directly modified by computer communications and then be saved;

   09. Online print:Any interface in the protection menu can be printed directly after computer communication;

   10. Communication function:With 485 communication mode.


Protective action principle

 protection for current instantaneous trip, protection for time delay current instantaneous trip, over current and Inverse time Over-current, over load、Zero sequence current instantaneous trip 、Zero sequence time delay current instantaneous trip、Zero sequence time delay  current instantaneous trip and Zero-Sequence definite time over-current , Inverse time over-current 、 Zero sequence time delay current instantaneous trip , over voltage, low voltage, system power loss、PT line-break、PT no-voltage、Low frequency load shedding、 loss of close circuit and trip circuit is the same as 9511 Line protection measurement and control device

Non electricity protection:(Including the output of the main transformer C6、Negative control trip C7、heavy Buchholtz C8、light Buchholtz C9、high Temperature C10、Temperature rise C11)


heavy Buchholtz

1).RLP15  heavy Buchholtz-“in service ”; 

2).C8 collect the signal;

3).protection immediate run B12/B13,Simultaneous drive accident signal relay B14/B15(Until the manual, before returning to the relay),the accident indicator of panel light.

Special note:

1).light Buchholtz, temperature rise only alarm function;

2).Negative control trip, the temperature is too high trip only trip function;

3).The input of main transformer can choose alarm or trip;

4).Corresponding to the above non electric quantity,In the "protection of investment back" if you choose“out of service”,Is the general opening amount,When the signal is collected,Neither alarm, nor trip, you can be define it in the background monitoring system other names.

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