Description
Product Overview
- The Transformer High Backup Protection Relay is designed for backup protection of transformers in substations at voltage levels of 110 kV and below. It works in conjunction with the AST-441H Differential Protection Unit to perform secondary functions for the main transformer bay.
Product Functions (ANSI)
- Voltage-Dependent Overcurrent Protection｜51V
- Residual Current Protection｜51N
- Thermal Overload Protection｜49
- Undervoltage Protection｜27
- Underfrequency Protection｜81U
- Overfrequency Protection｜81O
- Inverse Overcurrent Protection｜51I
- Current Unbalance Protection｜46
- Overvoltage Protection｜59
- VT (Voltage Transformer)
Communication Mode
- Optional: RS-485, CAN bus, Ethernet, IEC 60870-5-103 (IEC-103)
Main Functional Specifications
| No. | Parameter Category | Parameter Name | Technical Specification |
|---|---|---|---|
| 1 | Protection Response Characteristics | Protection Response Time (including output relay response time) | Average error in response time: ≤ 35 ms |
| 2 | Operating Range & Setting Accuracy | Precision Operating Range – Current | Minimum precision current: 0.08 In; Maximum precision current: 20 In |
| 3 | Operating Range & Setting Accuracy | Current Setting Error | When current exceeds 1.00 A, error shall not exceed ±2.5% |
| 4 | Operating Range & Setting Accuracy | Voltage Setting Error | Error shall not exceed ±3% |
| 5 | Measurement Accuracy | Current (I) / Voltage (U) Measurement Accuracy | Class 0.2 |
| 6 | Measurement Accuracy | Active Power (P) / Reactive Power (Q) Measurement Accuracy | Class 0.5 |
| 7 | Other Performance Indicators | Remote Signal (SOE) Resolution | ≤ 2 ms |
Event Logging, Fault Recording
- Recorded events consist of protection actions and device faults.
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It records trip type, trip time and on-site operating parameters during tripping.
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Fault records include protection operation time, operation type and RMS values pre and post recording.
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Fault waveform: 2 cycles before fault, 4 cycles after fault.
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Up to 48 SOE records and 16 fault reports can be retained after power outage.
Monitoring Features
- The Transformer High Backup Protection Relay measures analog parameters including current, voltage and frequency.
- It acquires status signals from circuit breakers, energy storage units, disconnectors and remote/local switches, along with other digital inputs. It also supports disconnector control functions.
Setting Table of Transformer High Backup Protection Relay
| No. | Parameter Name | Setting Range | Step Multiplier |
|---|---|---|---|
| 5 | Stage 1 Overcurrent Protection Time Delay (T1) | 0～120.00 s | ×100 |
| 6 | Stage 2 Overcurrent Protection Time Delay (T2) | 0～120.00 s | ×100 |
| 7 | Stage 3 Overcurrent Protection Time Delay (T3) | 0～120.00 s | ×100 |
| 8 | Spare | – | – |
| 9 | Stage 1 Zero-sequence Overcurrent Protection Time Delay (T01) | 0～120.00 s | ×100 |
| 10 | Stage 2 Zero-sequence Overcurrent Protection Time Delay (T02) | 0～120.00 s | ×100 |
| 11 | Zero-sequence Overvoltage Protection Time Delay (T0V) | 0～120.00 s | ×100 |
| 12 | Overload Protection Time Delay (TOL) | 0～120.00 s | ×100 |
| 13 | Undervoltage Protection Time Delay (TUV) | 0～120.00 s | ×100 |
| 14 | Under-frequency / Phase Loss Protection Time Delay (TUF/PL) | 0～120.00 s | ×100 |
| 15 | Stage 1 Overcurrent Protection Setting (Instantaneous Trip Current Setting) | 0.40～99.99 A / 0.10～20.00 A | ×100 |
| 16 | Stage 2 Overcurrent Protection Setting (Time-limited Instantaneous Trip Current Setting) | 0.40～99.99 A / 0.10～20.00 A | ×100 |
| 17 | Stage 3 Overcurrent Protection Setting (Overcurrent Protection Current Setting) | 0.40～99.99 A / 0.10～20.00 A | ×10 |
| 18 | Overload Protection Setting (Overload Current Setting) | 0.40～99.99 A / 0.10～20.00 A | ×100 |
| 19 | Stage 1 Inverse-time Overcurrent Protection Current Setting (Original Start-up Setting) | 1～99.99 A | ×100 |
| 20 | Stage 1 Zero-sequence Overcurrent Protection Setting | 0.02～5.00 A / 0.40～99.99 A | ×100 |
| 21 | Stage 2 Zero-sequence Overcurrent Protection Setting | 0.02～5.00 A / 0.40～99.99 A | ×100 |
| 22 | Zero-sequence Current Blocking Setting (Zero-sequence Current for Zero-sequence Overvoltage Blocking) | 0.02～5.00 A / 0.40～99.99 A | ×100 |
| 23 | Undervoltage Blocking Setting (Undervoltage for Overcurrent Protection Blocking) | 5～100.00 V | ×100 |
| 24 | Negative-sequence Voltage Setting (Negative-sequence Voltage for Overcurrent Protection Blocking) | 5～100.00 V | ×100 |
| 25 | Zero-sequence Overvoltage Protection Setting | 5～100.00 V | ×100 |
| 26 | Zero-sequence Voltage Blocking Setting (Zero-sequence Voltage for Zero-sequence Overcurrent Blocking) | 0～100.00 V | ×100 |
| 27 | Undervoltage Protection Setting (Undervoltage Trip Setting) | 0～100.00 V | ×100 |
| 28 | Under-frequency Protection Setting | 0.2～10.00 Hz | ×100 |
| 29 | Stage 1 Inverse-time Overcurrent Protection Time Delay | 0～120.00 s | ×100 |
| 30 | Current Unbalance Protection Time Delay | 0～120.00 s | ×100 |
| 31 | Current Blocking Setting (Low Current for Under-frequency Protection Blocking) | – | – |
| 32 | Voltage Blocking Setting (Low Voltage for Under-frequency Protection Blocking) | – | – |
| 33 | Frequency Slip Setting | – | – |
| 34 | Stage 2 Inverse-time Overcurrent Protection Time Constant | 0～120.00 s | ×100 |
| 35 | Stage 2 Inverse-time Overcurrent Protection Current Setting | 1～99.99 A | ×100 |
Outline and Installation Dimensions
FAQ
Q：What is transformer backup protection?
A:The primary scope of Transformer High Backup Protection Relay covers the areas outside the bushing. When a fault occurs externally, the transformer backup protection device operates; it also serves as the transformer’s secondary backup protection, activating when the main protection fails to operate.
Q：How to Install and Use a Transformer Backup Protection Device
A:When selecting backup protection devices for transformers, it is necessary to consider their protective functions and other technical parameters. Equipment such as transformer differential protection devices and non-electrical quantity protection devices should be installed together in a single control panel.
Q: What are the main protection functions?
A: Voltage restrained phase overcurrent, zero-sequence earth overcurrent, overvoltage and undervoltage backup protection.
xiao zhang –
The relay monitors HV side voltage and current in real time. For system short-circuit or grounding faults that primary differential protection fails to cut off, it operates with preset delay to trip the breaker. Voltage restraint avoids misoperation under normal overload conditions.
Jack –
Sensitive and selective coordination — avoids unnecessary outages.