The relay protection tester is a specialized instrument used in the power system to verify the performance of relay protection devices. With the widespread adoption of microcomputer protection, the traditional voltage regulator and phase shifter combination has been replaced by more powerful microcomputer relay protection testers. In practical work, the selection, application, and test standards form a mutually interrelated complete chain: first, the selection grade is determined based on the application scenario, and then the verification and use are carried out according to the standards. The following will be discussed from these three dimensions.
1. Application Scenario Determines Selection Strategy
The core principle of selection is “satisfy current needs and appropriately adapt to future development”. Different voltage levels and application environments have significant differences in the requirements for the tester.
Low-voltage distribution network (0.4kV – 10kV)
Typical applications include distribution terminal (FTU/DTU/TTU), single-phase grounding protection, and small motor protection. For such scenarios, a single-phase or simple three-phase tester is recommended to meet the basic overcurrent and grounding protection verification. The selection focuses on portability and cost-effectiveness. Portable models are often required for on-site maintenance, and the weight should be controlled within 20kg, preferably with built-in lithium batteries.
Medium-voltage distribution network (10kV – 35kV)
Typical applications include line overcurrent protection, transformer differential protection, and backup auto-switching device. The recommended configuration is a standard three-phase tester (3 voltage + 3 current), which is the mainstream configuration for power maintenance teams, sufficient to simulate common faults such as three-phase short circuits and single-phase grounding. The selection focuses on functional balance, it needs to support harmonic superposition and fault transient simulation, and also consider certain portability.
High / Ultra-high voltage (110kV and above)
Typical applications include busbar differential protection, high-voltage line distance protection, and generator-transformer group protection. The recommended configuration is a six-phase / multi-phase high-precision tester (such as 6 voltage + 6 current), it must support digital protection verification, and be compatible with IEC 61850 protocols (GOOSE, SV sampling values). The selection focuses on high precision and comprehensiveness, the output accuracy requirement is ≤ 0.1%, it needs to support GPS synchronization testing (for longitudinal protection) and fault playback functions.
Smart substation (special scenarios)
Typical applications include merging unit (MU), intelligent terminal, and protection measurement and control integrated device. The recommended configuration is a digital integrated tester, the core indicators are the number of optical Ethernet ports (at least 2, independent receiving and transmitting), and it must support IEC 61850-9-2/9-2LE and IEEE 1588 time synchronization protocols. The selection focuses on protocol compatibility, it is necessary to confirm that the equipment supports the specific message format of the smart station, which cannot be replaced by traditional analog testers.
2. Core Selection Indicators
Regardless of the application scenario, the following hard indicators need to be focused on.
Output accuracy: For high-voltage systems, it should be ≤ 0.1%, for conventional distribution networks, it can be relaxed to 0.5%, phase accuracy should be ≤ 0.1°.
Current capacity: For conventional, it needs 30A / phase, for large transformers or busbar protection testing, it is recommended 75A or above, and attention should be paid to short-term output capacity (such as 100A / 1 second).
Software functions: It is necessary to check if it has an automatic test module for target protection (such as differential, distance curve scanning), and if it supports COMTRADE format fault recording playback.
3. Core Test Standard System
When using the tester, it is necessary to follow the complete standard chain from device design to on-site inspection.
Product and test basic standards
GB/T 7261 “Basic Test Methods for Relay Protection and Safety Automatic Devices” is the most core basic standard, it stipulates the test conditions and general methods for various protection devices, the design of the tester should meet its requirements.
DL/T 624 “Technical Conditions for Microcomputer-Based Test Equipment for Relay Protection” is a standard specifically formulated by the power industry for microcomputer testers, clearly defining technical parameters, inspection rules, and modern interfaces (such as Ethernet, GPS) specifications.
Calibration and Value Traceability Standard
DL/T 1153—2025 “Calibration Specification for Relay Protection Test Instruments” will come into effect on June 18, 2026, replacing the 2012 version. This standard is applicable to the calibration of analog, digital, and digital-analog integrated test instruments, and is a new basis for ensuring the reliability of the tester’s own accuracy. It is recommended that the calibration cycle for in-use test instruments be one year, and they should be sent to qualified institutions for periodic calibration.
Field Inspection Work Standard
DL/T 995 “Inspection Procedures for Relay Protection and Grid Safety Automatic Devices” is a guiding document for conducting regular inspections of protection devices on-site. All test items, methods, and qualified criteria must follow this procedure.
Post time: Sep-17-2026