Nanjing Nanzi PSM691U motor differential protection device

Nanjing Nanzi PSM691U motor differential protection device

1 Function
1. Differential protection
2. Differential quick break protection
3. Differential current out of limit alarm
4. TA disconnection locking
5. Current quick break protection
6. Definite time overcurrent protection
7. Two section definite time negative sequence protection/inverse time negative sequence protection
8. Overheating protection
9. Locked rotor protection
10. Single phase grounding protection
11. Low voltage protection
12. Overload protection
13. Non electric quantity protection
14.4-20mA output
15.9 fault recording and 2 startup recording
16. I, U, P, Q, Cos φ active kilowatt hour, reactive kilowatt hour, 14 channel switching value acquisition
17. GPS time synchronization (minute pulse, second pulse or IRIG-B mode)

Nanjing Nanzi PSM691U motor differential protection device

2.2 Differential quick break protection
When any differential current is greater than the setting value of differential quick break protection, the protection device will have no delay outlet.
2.3 Differential current out of limit alarm
When the device detects that any differential current value reaches the setting value of differential current out of limit alarm, it will send an alarm signal after a certain delay.
2.4 TA disconnection alarm
When the short lead runs at rated current and any phase TA on either side is disconnected, the device can send a signal or lock the differential according to the control word.
2.5 Current quick break protection
The current of asynchronous motor is very large during starting, usually up to 5~8 times of rated current (Ie), and the starting time can be up to tens of seconds. The device is set with two quick break settings. During the starting process, the "mid start quick break setting value" is used. The value is set to avoid the starting current of the motor. After the motor is started, the "quick break setting value after starting" is automatically used. The value is considered as the self starting current of the motor and the large feedback current of the motor when the external outlet is short circuited. The larger of the two currents is taken.

a、 The starting time tst is set to avoid a long starting time, tst>tst.max.
b、 The setting value Iop. h during startup is set by avoiding the starting current Ist of the motor, namely:
When t ≤ tst, Iop. h=krel × Ist. To avoid the influence of aperiodic components, krel is taken as 1.5, Ist is (6~8) Ie.
c、 The setting value Iop. l during operation is set to avoid the self starting current and the large feedback short circuit of the motor in case of short circuit at the outlet of the zone. The size of the self starting current is related to the delay of automatic switching of the standby power supply and other factors. When the fast switching of the auxiliary power supply is successful, the motor almost has no self starting process, because the speed has not been significantly reduced, only when the residual voltage switching or synchronous capture switching, The motor speed has significantly decreased, and the self starting current will be larger. According to the traditional method, the self starting current Iast=5Ie, Iop. l=krel × Iast × Ie=1.3 × 5 × Ie=6.5Ie. The three-phase short circuit at the outlet of the zone considers the inherent delay of protection (40~60) ms, and the feedback current Ifb=6Ie. Iop.l=krel×Ifb=1.3×6Ie=7.8Ie。
d、 The short time delay of quick break protection is used to cooperate with F-C circuit.
2.6 Definite time overcurrent protection
When the three-phase current IA, IB and IC of the motor are greater than the setting value of overcurrent protection, it will pass the time delay outlet. The overcurrent setting can be set according to the starting current, generally (1.2~2) Ie. The time delay is set to avoid the starting time of the motor.
2.7 Two section definite time negative sequence overcurrent protection/inverse time negative sequence protection
When three-phase voltage imbalance, phase failure, reverse phase and inter turn short circuit occur in the motor, negative sequence current will be generated. Positive sequence current is I1, negative sequence current is I2......