I. Selection of basic current and voltage phase numbers
The configuration of current and voltage phase numbers for the equipment is entirely based on the actual test object and application scenario. The applicable scenarios of different configurations are clearly defined:
1. Three-phase voltage + three-phase current: This is the basic general configuration, which can cover all conventional test scenarios such as line protection, overcurrent protection, and instantaneous protection in 35kV and below distribution systems, meeting the daily basic debugging requirements.
2. Four-phase voltage + three-phase current: On the basis of the three-phase configuration, a zero-sequence voltage or open delta voltage channel is added to specifically adapt to special scenarios that require synchronous function testing.
3. Six-phase voltage + six-phase current: Currently, this is the mainstream high-end configuration in professional debugging, mainly used for transformer differential protection, busbar protection, etc. It can simultaneously increase the load on both the high and low voltage sides and multiple sides of the equipment, significantly improving the testing efficiency and debugging flexibility in complex working conditions.
II. Selection of test accuracy indicators
Accuracy indicators are the core indicators that determine the authority of the test results and control the economic efficiency of on-site construction. The difference of 0.1% and 0.2% in accuracy has a significant impact on actual work.
When conducting core tests such as protection setting verification and characteristic curve scanning, the output accuracy of the equipment’s current and voltage must be better than 0.1%. If the accuracy does not meet the standard, it is very likely to cause the protection device to fail the verification, leading to equipment rework, re-inspection, etc. Especially in the construction scenario of 220kV substations, a single-day shutdown and rework may result in economic losses of tens of thousands of yuan.
From an industry standard perspective, the actual measured accuracy of the AC output of high-performance equipment in the industry can reach 0.1%, which conforms to the official detection standard of the Electric Power Research Institute. The qualified accuracy range for industry use is 0.1%-0.2%, and high-precision equipment is more suitable for high-voltage and high-standard debugging scenarios.
III. Software function selection (equipment soft power)
Software functions directly determine the operability and intelligence level of the equipment. It is the core reference dimension for the selection of relay protection testers, and focuses on three major types of functions:
1. Core essential test modules: It is necessary to confirm in advance the pre-set dedicated test modules that are compatible with the working scenarios of the equipment. Core include the state sequence module, differential protection dedicated test module, and harmonic test module. The state sequence can simulate reclosing, automatic reclosing, etc., and the differential protection module can automatically draw the ratio braking curve to meet the special debugging needs.
2. Advanced fault analysis function: For the debugging of intelligent substations and complex power fault analysis scenarios, the equipment needs to support Comtrade format fault recording playback and system oscillation simulation functions, which can accurately replay fault conditions and simulate abnormal grid states.
3. Efficient office support design: Graphical Chinese operation interface, one-click generation of standardized test reports, and custom test template library functions can effectively simplify the on-site operation process, shorten the testing and data organization time, and significantly improve the efficiency of the front-line staff.
IV. Portability and power supply mode selection
The portability and power supply method of the equipment need to be comprehensively considered based on the fixed working scenarios, and be adapted to different working environment requirements:
1. Laboratory, factory debugging scenarios: The working environment of this scenario is fixed, and there is no need to frequently move the equipment. Priority should be given to the comprehensive functionality and test accuracy of the equipment, and there are no strict requirements for the volume and weight of the equipment.
2. On-site commissioning, outdoor maintenance scenarios: Portability is the core hard requirement. Prioritize equipment with a weight of less than 15kg and a sturdy and wear-resistant body structure; at the same time, pay close attention to the power supply method, prioritize models with built-in batteries or DC power supply, which can effectively address the operational difficulties of substations without AC external power supply, avoiding equipment power supply limitations and reducing the labor intensity of outdoor mobile operations.
V. Long-term compatibility selection of equipment To avoid rapid obsolescence of equipment and extend its service life, when selecting equipment, special attention should be paid to the equipment’s scalability and the ability to adapt to the standards of smart substations.
Even though traditional protection testing work is the main focus at present, priority should be given to choosing equipment that reserves optical digital interfaces, and the equipment should be compatible with the IEC 61850-9-2 SV sampling value protocol and the GOOSE general substation event protocol, to reserve space for future smart substation testing.
At the same time, priority should be given to selecting models that support online software upgrades. Through subsequent software iterations, the equipment can adapt to new communication protocols added by the industry and new testing functions, continuously update its performance, and ensure long-term usability.
Six. Equipment Operation Safety Prohibitions
During on-site testing operations, strict adherence to equipment operation norms is required to avoid core safety prohibitions and prevent equipment damage and safety accidents:
1. Strictly prohibit abnormal operation of the channel: The voltage output channel must not be short-circuited, the current output channel must not be open-circuited, and any illegal operation must be avoided to prevent equipment failure.
2. Strictly prohibit introducing external power sources: It is prohibited to connect any external AC or DC power sources to the voltage, current, and output signal output sockets of the tester. Otherwise, it will directly cause equipment damage.
3. Must be reliably grounded: Before the test operation, the equipment grounding terminal must be completed for reliable grounding of the host to effectively avoid static interference and electromagnetic interference, ensuring accurate test data and safety of the operation.
4. Ensure equipment cooling: After the equipment performs large current output operations, at least 30 seconds of cooling time must be reserved before conducting the next test. It is strictly prohibited to block the ventilation ports of the machine body to avoid overheating protection and component damage.
Seven. Selecting Equipment According to Voltage Levels
Different voltage levels of power systems have significant differences in the requirements for the functions and configurations of the testers. They need to be matched with specific models:
1. 0.4kV – 10kV system: Suitable for single-phase type and handheld portable equipment, meeting the basic requirements of being lightweight, battery-powered, and easy to operate, capable of completing basic verification tasks such as overcurrent protection and grounding protection.
2. 10kV – 110kV conventional substations: The four-phase voltage + three-phase current model has the best cost performance and can fully cover distance protection, zero-sequence protection, and most of the station protection types such as conventional differential protection. It is suitable for regular team debugging work.
3. 220kV and above high and ultra-high voltage substations: Must select six-phase voltage + six-phase current models, relying on the independent output capability of multiple channels to meet the testing needs of complex protections such as busbar differential and large transformer differential.
4. Smart substations: Not limited by voltage levels, uniformly select optical digital or digital-analog integrated equipment. The core requirement is to be compatible with the two core communication protocols of IEC 61850-9-2 and GOOSE.
Eight. Core Function of State Sequence
State sequence is the core basic function module of the relay protection tester, mainly used to simulate the complex sequential logic of the power system. It is the core support for various dynamic fault tests.
This function supports custom editing of multiple consecutive dynamic test states. Each state can independently set voltage, current, and frequency parameters, and freely define state switching conditions, including timed switching, input signal triggering, and manual triggering, etc. The core application scenarios are as follows:
1. Reclosing test: Completely simulate the full time sequence process of fault triggering, switch tripping, line reclosing, and accelerated fault tripping.
2. Backup auto-switching test: Simulate the complete logic process of main power source failure, backup auto-switching device action, and standby power supply input.
3. Synchronization device test: Precisely simulate the voltage difference and frequency difference of the standby side and the system side, and verify the capture and action conditions of the synchronization device.
If the daily work mainly focuses on line protection and automation device debugging, it is necessary to carefully confirm the equipment’s equipped functions and adjustable parameters of the state sequence module.
Ten. Selection of Input and Output Interface Configurations The number of input and output channels directly determines the complexity of the test adaptation capability of the equipment and is an important detail indicator for selection:
1. Input channels: They are mainly used to receive various action signals from protection devices. It is recommended to have at least 8 channels. The more channels there are, the more tripping, reclosing, alarm and other signals that can be monitored simultaneously, which can effectively improve the efficiency of the entire test and multi-signal linkage test.
2. Output channels: They are mainly used to simulate the position contacts of circuit breakers for closing and opening, and to trigger actions of external devices. It is recommended to have at least 2 pairs.
In complex tests such as backup auto-switching and full station group transmission, synchronous monitoring of multiple signals is the foundation for the smooth conduct of the test, and insufficient interface channels will directly limit the test scenarios and reduce the work efficiency.
X. Selection of current and voltage output capacity
The current and voltage output capacity of the equipment needs to be selected based on the type of the tested equipment and the test scenario, and at the same time, attention should be paid to the continuous output capacity:
1. Routine line protection test: Output capacity of single-phase 30A – 50A current and single-phase 120V voltage can meet the debugging requirements of most routine line protections.
2. Large main transformer and busbar protection test: It is necessary to adapt to a larger current output capacity. It is recommended to have single-phase 75A or above, which can meet the special testing requirements of large-capacity CT secondary circuits and adapt to the debugging of complex high-voltage equipment.
3. Portable handheld devices: The single-phase output current is usually below 10A and is only suitable for rapid detection in 10kV and below low-voltage power distribution systems, and cannot meet the test scenarios of high-voltage main transformer differential protection and other large-load testing.
In addition, attention should be paid to the duration of the large current output of the equipment. Most equipment has a short-time working mode for large current output, such as 30A current can only be sustained for 1 – 10 seconds. Long-term full-load output will trigger the overheating protection of the equipment, and it is necessary to match the test conditions of the equipment.
Post time: Jul-01-2026