Transformer protection device

♦ Two stage over current protection

♦ Inverse-time overcurrent protection

♦ Over load protection

♦ High voltage side of zero sequence over-current protection

♦ Low voltage side of zero sequence overcurrent protection

♦ Non-electricity protection

♦ PT breaking protection

♦ I、U、P、Q、cosφ、Hz、8 road switch quantity gathering

1 Protection function

1）Two stage over current protection

Each stage is respectively provided a soft linking piece were protection function of cast back and each section protection the a operating current and operating time of fixed value, Each stage of protection is independent of each other.

The action condition:

a）I> Overcurrent protectioncurrent setting value 

b）T> Overcurrent protection time setting value

c）Overcurrent i protection control word- simple over curren

2）I nverse time overcurrent protection

The protection function by controlling the word choice cast back, setting a threshold value and inverse time current inverse time constant.

The inverse time characteristic equation is as follows: 

: Inverse time current threshold value; : Overcurrent time coefficient value 

The action condition:

a）I>I nverse time overcurrent protectioncurrent setting value

b）T>Inverse time overcurrent protectiontime setting value

c）Inverse time overcurrent protectioncontrol word:1-ON

3）Overload protection

When any phase current is greater than the set current, the time delay trip or alarm. 

The action condition:

a）I > Overload protectioncurrent setting value

b）T>Overload protectiontime setting value

c）CB is in closed position 

d）Overload protectioncontrol word: 1-Trip  2-Alarm 

4）High voltage side zero sequence overcurrent protection 

When the high voltage side of the transformer 3I0 is larger than the setting value, the time delay device trip or alarm.

The action condition:

a）Io>Highzero sequence over-currentprotection current setting value 

b）T>Highzero sequence over-currentprotectiontime setting value

c）Highzero sequence over-currentprotectioncontrol word:1-Trip  2-Alarm

5）Low voltage side zero sequence overcurrent protection 

When the Low voltage side of the transformer 3I0 is larger than the setting value, the time delay device trip or alarm.

The action condition:

a）Io>Low zero sequence over-currentprotection current setting value 

b）T>Low zero sequence over-currentprotectiontime setting value

c）Low zero sequence over-currentprotectioncontrol word:1-Trip  2-Alarm

6）Non electricity protection 

The protection function is the standard configuration. Provide a direct jump interface for heavy gas, light gas, over temperature tripping and high temperature alarm. And through the control word to select the time delay trip / alarm, while the acquisition of remote signal. 

7）PT breaking protection

Any difference between the two phase voltage >18V; Umin<0.1Un. I have a current (>0.8In); meet the above criteria, sentenced to TV break, delay 10s alarm, report "TV breaking alarm". 

8）Control loop break 

CB control loop is normal, the TWJ and HWJ are in a state of 1 and the other one is 0. the two are 1 or 0, It shows that the control loop or the DI loop is abnormal, the 10s delay times "control loop break".