NSR631RF-D Transformer Protection and Control Device

NARI Group Corporation NSR631RF-D Transformer Protection and Control Device

NSR631RF-DA is an integrated protection and control device for station transformers/grounding transformers, providing protection, measurement and control, operation, and other functions for station transformers/grounding transformers. NSR631RF-DB is an integrated protection and control device for grounding transformers.
1 Function Configuration
Main protection functions include:

1) Three-stage overcurrent protection on the high-voltage side;

2) Three-stage directional zero-sequence overcurrent protection on the high-voltage side
(NSR631RF-DA); Three-stage directional zero-sequence overcurrent protection for ungrounded systems on the high-voltage side (NSR631RF-DB);

3) Two-stage
zero-sequence overcurrent protection on the low-voltage side;

4) Overload alarm;

5) External non-electrical quantity input protection.
Main measurement and control functions include:

1) Collection of 23 remote signaling inputs, device remote signaling status change, SOE recording;

2) Normal circuit breaker remote control opening and closing;

3) 19 remote measurements including Ia, Ib, Ic, Ua, Ub, Uc, Ioh, Uab, Ubc, Uca, 3Uo, Pa, Pb, Q, S,
φ, Fr;

4) Event SOE.
2 Working Principle
2.1 Three-Stage Overcurrent Protection on High-Voltage Side
NSR631RF-D is equipped with three-stage overcurrent protection (instantaneous overcurrent, Stage I overcurrent, Stage II overcurrent protection), each stage has independent current setting, time setting, and control word.

2.2 Zero-Sequence Overcurrent Protection on High-Voltage Side
1) Three-stage directional zero-sequence overcurrent protection
NSR631RF-DA is equipped with three-stage zero-sequence overcurrent protection, each stage has independent current setting and time setting; zero-sequence current can be selected via control word to use external or self-generated method ("Zero-sequence current self-generated" set to 0: zero-sequence current uses external CT method; set to 1: zero-sequence current uses self-generated method).
Zero-sequence overcurrent Stage I and Stage II are fixed to trip; zero-sequence overcurrent Stage III can be selected via control word to trip or alarm ("Zero-sequence Stage III protection trip" set to 1: trip; set to 0: alarm only).
Three-stage zero-sequence overcurrent can be blocked by direction. The grounding method is selected via control word "Neutral point grounding" (set to 1: directly grounded system or low-resistance grounded system; set to 0: ungrounded system). For ungrounded systems, the directional sensitive angle is 90° (zero-sequence voltage leads zero-sequence current by 90°); for grounded systems, the directional sensitive angle is -110° (zero-sequence voltage lags zero-sequence current by 110°).
2) Three-stage directional zero-sequence overcurrent protection for ungrounded systems
NSR631RF-DB is equipped with three-stage zero-sequence overcurrent protection, each stage has independent current setting and time setting; zero-sequence current can be selected via control word to use external or self-generated method ("Zero-sequence current self-generated" set to 0: zero-sequence current uses external CT method; set to 1: zero-sequence current uses self-generated method).
Zero-sequence overcurrent Stage I and Stage II are fixed to trip; zero-sequence overcurrent Stage III can be selected via control word to trip or alarm ("Zero-sequence Stage III protection trip" set to 1: trip; set to 0: alarm only).
Three-stage zero-sequence overcurrent can be blocked by direction. The directional sensitive angle is 90° (zero-sequence voltage leads zero-sequence current by 90°).

2.3 Zero-Sequence Overcurrent Protection on Low-Voltage Side
NSR631RF-D is equipped with two-stage zero-sequence overcurrent protection on the low-voltage side, each stage has independent current setting and time setting.

2.4 Overload Protection
NSR631RF-D is equipped with overload protection on the high-voltage side. Overload protection is fixed to alarm.

2.5 Non-Electrical Quantity Protection
NSR631RF-D is equipped with 4 non-electrical quantity protection circuits, which can be selected via control word to trip or alarm. The logic for all 4 non-electrical quantities is consistent.

2.6 High-Voltage Side Bus PT Break Alarm
Bus PT break alarm is judged with current blocking, i.e., when all three-phase currents are less than 0.05In, the element is disabled. Bus PT break uses line voltage drop and negative-sequence voltage rise criteria, with a 10s delay after activation to alarm. Its operating value, return value, and the "PT secondary rated value" in system parameters are related:
When the setting is 100V, it activates when line voltage is less than 70V and returns when greater than 80V; it activates when negative-sequence voltage is greater than 10V and returns when less than 7V;
When the setting is 220V, it activates when line voltage is less than 154V and returns when greater than 176V; it activates when negative-sequence voltage is greater than 22V and returns when less than 15V.

2.7 Auxiliary Alarms
NSR631RF-D device has auxiliary alarm functions such as control circuit break, spring not charged, TWJ abnormal, CT abnormal, frequency out-of-limit, etc.; among these, control circuit break alarm and spring not charged alarm can be enabled or disabled, other alarms are fixed enabled.
1. Control circuit break: Both TWJ and HWJ are 1 or 0, alarm after 10s delay; if the device is not configured with an operation board, this alarm function should be disabled;
2. Spring not charged: External "spring not charged" has input, alarm after 10s delay;
3. TWJ abnormal: Line has current but TWJ is 1, alarm after 10s delay;
4. CT break: Larger phase current is greater than 4 times the smaller phase current, alarm after 10s delay; when load is too small, CT break judgment is not performed;
5. Frequency out-of-limit: Frequency exceeds the range of 45Hz to 55Hz, alarm after 10s delay.

2.8 Measurement and Control Functions
1. Remote control functions mainly include two types: remote trip operation, remote close operation.
2. Remote measurements mainly include: Ia, Ib, Ic, Ua, Ub, Uc, Ioh, Uab, Ubc, Uca, 3Uo, Pa, Pb, Q, S, φ, Fr; and active energy, reactive energy calculated through integration; with 7th harmonic analysis capability.
4. Remote signaling mainly includes: 23 remote signaling input collection, synthesized double-point remote signaling, general accident remote signaling, and event sequence recording,