Motor protection device

♦ Motor Fast-Tripping protection

♦ Phase overcurrent protection

♦ Negative sequence overcurrent protection

♦ Inverse-time overcurrent protection

♦ Motor long start protection

♦ Motor locked rotor protection

♦ Motor overload protection

♦ Zero sequence over-current protection

♦ Over voltage protection

♦ Low voltage protection

♦ PT breaking protection

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

1 Protection function

1）Motor Fast-Tripping protection

Motor in the starting process is very large, usually can reach 5 to 8 times the rated current (Ie), start time can be up to several tens of seconds. Device is equipped with two speed posit values, in machine process the start speed determine the value and the value to avoid motor starting current setting, motor starts after the end of the process, automatically using "after speed determine the value and the value according to the motor start current and short-circuit export from the time the maximum motor feedback current account, take two of the big one in the current.

2）Phase overcurrent protection

The protective function of the soft plate is put back, and the protection has an action current and the action time value, When any phase current is greater than the setting value.by the time delay tripping device.

The action condition:

a）I> Phase overcurrent protection current setting value

b）T> Phase overcurrent protectiontime setting value

c）Phase overcurrent protection control word:1-ON

3）Negative sequence overcurrent protection 

When the motor has the unbalanced three-phase voltage, phase failure, reverse phase, inter-turn short circuit, will produce negative sequence current. 

The action condition:

1）I2>Negative sequence overcurrent protection current setting value

2）T>Negative sequence overcurrent protection setting value

3）Negative sequence overcurrent protection control word:1-ON

4）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

5）Motor long start protection 

In view of the long starting time of the motor due to the slight blockage and other reasons, the motor protection and control device is set up to protect the starting time, and the control function of the independent press plate is dropped. 

The action condition:

1）T>Tstart； Tstart：Motor start time

2）I>2Ie；    Ie:Rated motor current

3） CB is in closed position 

4）Long startup time protection control word:1-ON,trip

6）Motor locked rotor protection 

Blocking protection is peculiar to the motor a protection, general motors in the course of its operation, if due to the load is too large or its mechanical reasons, causing the motor shaft is stuck (commonly known as "brake"), depending on the overload capacity, allowing running time is short, but if not promptly removed this fault will cause overheating of the motor winding, insulation to reduce burn motor, thus blocking protection is to avoid the type of fault in a powerful weapon. Motor protection and control device to provide a complete and independent blocking protection logic protection function by switching control word selection. In the current setting value is greater than the torque current and rotational speed in the closed contact is open, can be set according to the time limit for blocking protection, fast tripping, avoid damage of the motor, reduce the direct and indirect economic losses. 

The action condition:

1）I>Locked rotor protection current setting value

2）T>Locked rotor protection time delay  

3）Speed contactDI is closed

4）Locked rotor protection control word:1-ON

7）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 

8）Zero sequence overcurrent protection 

When the zero sequence overcurrent protection is larger than the setting value, the time delay device trip or alarm.

The action condition:

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

b）T>Zero sequence over-currentprotectiontime setting value

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

9）Overvoltage protection

When the voltage is greater than the set value and CB is in closed position,, the time delay trip or alarm. 

The action condition:

a）Max(UAB、UBC、UCA)>Overvoltage protection voltage setting value

b）T>Overvoltage protection time setting value

c）CB is in closed position 

d）Overvoltage protection control word: 1-Trip  2-Alarm 

10）Low voltage protection

When the voltage is less than the set value and CB is in closed position, the time delay trip or alarm.

The action condition:

a）Max(UAB、UBC、UCA)< Low voltage protectionvoltage setting value

b）T>Low voltage protectiontime setting value

c）CB is in closed position 

d）Low voltage protectioncontrol word: 1-Trip  2-Alarm 

11）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". 

12）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".