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Leon Zhang sales consultant
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Email: zxl635973785@gmail.com
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Phone/WhatsApp: +86 13655813266
Transformer High Backup Protection Relay
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)
51V, 51N, 49, 27, 81U, 81O, 51I, 46, 59
Communication Mode
- Optional: RS-485, CAN bus, Ethernet, IEC 60870-5-103 (IEC-103)
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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.
Q: What is Transformer High Voltage Backup Protection Relay?
A: It serves as the backup protection for the high-voltage side of power transformers, acting as a backup when main differential protection fails or external faults occur on the HV side, adjacent lines and busbars.
Q: What core protection functions does it include?
A: It covers three-phase time-limit overcurrent, zero-sequence earth backup overcurrent, negative-sequence overcurrent, overload monitoring and voltage locking overcurrent protection.
Q: What faults can this backup protection respond to?
A: It trips for external short-circuit faults on HV side outgoing lines, busbar faults, transformer winding external short circuits, single-phase earth faults and prolonged severe overload conditions.
Q: What is the difference between main differential protection and HV backup protection?
A: Differential protection is primary protection for transformer internal faults with fast tripping. HV backup protection acts with intentional delay to back up main protection and adjacent equipment faults.
Q: Can the action delay and setting values be modified on site?
A: Yes. All current thresholds, voltage locking conditions and multi-stage time delays can be edited locally with password access or remotely via the background monitoring system.
Q: What signals need to be wired into this relay?
A: Three-phase CT currents and PT voltage signals from the transformer high-voltage side, circuit breaker position auxiliary contacts, DC trip circuit and remote signal wiring terminals.
Q: Does it support blocking logic to prevent maloperation?
A: It can be interlocked with breaker status, manual trip signals and maintenance locking signals to avoid incorrect tripping during switching operation and equipment overhaul.
Q: Which communication protocols are compatible?
A: Standard protocols include Modbus-RTU, Modbus-TCP and IEC 60870-5-104; IEC 61850 MMS and GOOSE are available as an optional upgrade.
Q: Will the relay record fault action data?
A: It stores fault event logs, action element information, fault electrical quantities and fault waveform records, which can be uploaded to SCADA for post-fault analysis.
Q: What power supply does the relay require?
A: The control and trip loop adopts DC 110V or DC 220V working power, matching the standard power supply specification of substation secondary protection panels.
Q: What accessories and documents are delivered together?
A: Principle schematic diagrams, terminal wiring drawings, parameter setting guide and factory test report are provided. The standard warranty period is 24 months from shipment.
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Professional Warranty: Reliable after-sales support for stable relay protection and long-term customer satisfaction.
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.