Guodian Nanzi PST645U Transformer Protection and Control Device

1 Overview

The PST 645U Transformer Protection and Control Device is suitable for station service transformers or grounding transformers in non-directly grounded systems or small resistance grounding systems with voltage levels below 110KV. It can be installed in panels or locally.
1.1 Protection Function Configuration
1) Three-stage composite voltage blocking overcurrent protection (Stage III can be set as inverse time)
2) Three-stage zero-sequence overcurrent protection on the high-voltage side (Stage III alarm/trip optional)
3) Three-stage zero-sequence overcurrent protection on the low-voltage side (Stage III can be set as inverse time)
4) Overload (alarm/trip optional)
5) Zero-sequence overvoltage protection (alarm/trip optional)
6) Undervoltage protection
7) Manual closing acceleration protection
8) 4 non-electrical protection circuits
1.2 Control Function Configuration
1) 22 external switch input telemetry collection;
2) Circuit breaker position, manual tripping, and accident telemetry;
3) Normal circuit breaker remote control opening and closing;
4) 2 pulse inputs, electric energy accumulation;
5) GPS time synchronization input (adaptive to minutes and seconds).

2 Device Performance
2.1 Basic Configuration:
1. Two-stage phase current protection for phase-to-phase faults
2. Overload alarm and/or trip function
3. Independently settable acceleration stage for automatic closing to fault conditions
4. Zero-sequence current protection for single-phase ground faults in directly grounded systems
5. Zero-sequence current protection can operate in either definite time or inverse time mode
6. Loss of voltage protection blocked by current and PT disconnection
7. Automatic PT disconnection detection
8. Non-electrical protection for transformers
2.2 Main Technical Performance
2.2.1 Accurate Operating Range of Sampling Circuit (5% Error)
Voltage: 0.4V～120V
Current: 0.08In－20In
2.2.2 Contact Capacity
Signal circuit contact current-carrying capacity: 400VA
Signal circuit contact arc-breaking capacity: 60VA
2.2.3 Trip and Closing Current
Circuit breaker trip current: 0.5A～6A (specify when ordering)
Circuit breaker closing current: 0.5A～6A (specify when ordering)
2.2.4 Accuracy of Various Components
Current element: < 5%
Voltage element: < 5%
Time element: < 20ms
2.2.5 Overall Operating Time (Including Relay Inherent Time)
Inherent operating time of the instantaneous stage:
Measured at 1.2 times the setting value, not exceeding 40ms
2.2.6 Analog Measurement Circuit Accuracy
For control devices equipped with measurement modules:
Current and voltage: Class 0.2
Power and energy: Class 0.5