Secondary Circuit Testing Equipment for Protective Relay Calibration and Substation Commissioning
Substation protection and control schemes rely on flawless secondary wiring loops to isolate faults and protect primary grid assets. Secondary circuit testing equipment encompasses specialized injection test sets and phase analysers engineered to verify protective relay logic, current transformer (CT) and voltage transformer (VT) secondary burdens, and tripping time coordination. Deploying precision secondary test systems ensures that digital and numerical relays operate selectively and reliably under simulated grid fault conditions, preventing catastrophic cascading outages.
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Microcomputer Protective Relay Test Sets: Multi-phase voltage and current output systems capable of executing automated end-to-end testing for distance, overcurrent, differential, and synchronizing relays.
Secondary Current Injection Test Sets: Delivers heavy-duty variable AC current outputs to verify thermal overload relay pickup thresholds, circuit breaker trip coils, and CT secondary burden impedances.
Voltammetry Phase Meters (Phase Angle Voltmeters): Measures multi-channel voltage-to-voltage, current-to-current, and voltage-to-current phase angles with high resolution to verify differential protection vector groups.
Power Quality Analyzers for Secondary Loops: Captures harmonic distortion, voltage sags, swells, and transient flickers within secondary control circuits and auxiliary power supplies.
Secondary Current Injection Testing Equipment: Specialized handheld or portable units designed for on-site verification of current loop continuity and polarity check during pre-commissioning.
Technical Specifications
| Parameter | Specification |
| AC Current Output Channels | 3 to 6 channels |
| AC Current Output Range | 0 to 30 A per channel |
| AC Current Output Accuracy | +/- 0.2% of reading |
| AC Voltage Output Channels | 4 channels |
| AC Voltage Output Range | 0 to 120 V line-to-neutral; 0 to 300 V line-to-line |
| AC Voltage Output Accuracy | +/- 0.1% of reading |
| Harmonic Generation | Up to the 21st harmonic overlaid on the fundamental frequency, with adjustable phase and amplitude |
| Phase Angle Measurement Range | 0 to 360 degrees |
| Phase Angle Resolution | 0.01 degrees |
| Phase Angle Accuracy | +/- 0.1 degrees |
| Auxiliary DC Power Supply | Adjustable 0 to 300 V DC output |
| DC Protection | Independent short-circuit protection and overload trip feedback |
| Enclosure Rating | IP54 |
| Enclosure Design | Ruggedized field transport casing with shock-absorbing internal chassis and sealed membrane keypad |
Key Features
High-Fidelity Linear Power Amplifiers: Employs linear amplification stages rather than switching power supplies for current channels, ensuring pure sinusoidal output waveforms with less than 0.1% total harmonic distortion (THD).
Automatic Transient Fault Simulation: Pre-programmed script engine generates complex multi-state dynamic transients, power swings, and reclosing sequences for advanced distance protection testing.
GPS / IRIG-B Time Synchronization: Supports satellite timing references for end-to-end distributed differential protection testing across geographically separated substations.
Transient Data Logging and Export: Internal non-volatile memory records up to 1,000 test reports, exportable via USB flash interface or Ethernet network protocols.
Direct PC Software Control: Comprehensive diagnostic software suite allows automated test template generation, vector diagram visualization, and direct report compilation conforming to international test formats.
Test Applications
Substation Commissioning and Acceptance Testing: Pre-energization verification of numerical relay trip logic, interlocking schemes, and tripping matrix verification in high-voltage switchyards.
Electric Utility Periodic Maintenance: Annual or bi-annual preventive calibration audits on transformer, busbar, and transmission line protection panels.
Switchgear Manufacturing Quality Control: Final functional testing of control wiring, auxiliary relays, and metering circuits on assembled medium-voltage switchgear line-ups.
Independent Testing Laboratories (NETA/ISO 17025): Third-party compliance auditing and forensic analysis following grid fault tripping investigations.
Final Solution
Determine Relay Protection Schemes
Basic distribution overcurrent protection requires simple 3-phase current and voltage test sets, whereas complex transmission line differential schemes require 6-phase test systems with GPS synchronization.
Evaluate Output Burden Requirements
Heavy electromagnetic electromechanical relays demand higher output power (VA burden) per channel, whereas modern numerical solid-state relays require high signal resolution and low distortion.
Consider Portability vs. Bench Utility
Field service commissioning engineers require lightweight, ruggedized transport cases with integrated touchscreens, while permanent laboratory test benches benefit from modular rack-mounted architecture.
Amplifier Thermal Management: Custom extruded aluminum heatsinks and temperature-regulated cooling fans maintain junction stability during sustained high-current injection tests.
Automated Calibration Loops: Precision voltage and current references calibrated against Fluke multi-product calibrators to verify linearity across all output ranges.
Full-Load Burn-In Chambers: Assembled mainboards undergo 48-hour continuous thermal cycling at +50 degrees Celsius to screen for semiconductor drift and component infant mortality.
Customization / OEM
Software Localization
Multilingual operational firmware and test reporting modules available in English, Spanish, French, Russian, and regional utility languages.
Hardware Adaptation
Custom output terminal layouts, specialized banana plug adapters, and front-panel corporate logo branding for regional distribution partners.
OEM/ODM Engineering
Modular software protocol integration tailored to proprietary utility automation and automated test equipment (ATE) production lines.
Documentation & Certifications
Compliance Standards
CE electrical safety and EMC immunity certification, ISO 9001 quality management system manufacturing compliance.
Calibration Documentation
Each unit ships with an individual factory calibration report carrying traceable serial numbers and verification waveforms.
Technical Deliverables
Comprehensive English operator manuals, wiring application notes, and software diagnostic utility packages.
Certifications
FAQ
Q: Why are linear amplifiers preferred over switching amplifiers in secondary current test sets?
A: Linear amplifiers provide superior signal fidelity and extremely low total harmonic distortion (THD), ensuring that the injected test currents remain pure sinusoids without high-frequency switching noise that could falsely trigger sensitive numerical relays.
Q: Can these test sets perform end-to-end testing of line differential protection schemes?
A: Yes. By utilizing integrated GPS or IRIG-B time synchronization modules, two separate test sets deployed at opposite ends of a transmission line can inject synchronized transient states simultaneously.
Q: What is the purpose of the auxiliary DC power supply output on the test set?
A: The variable auxiliary DC power supply provides clean, isolated operating voltage (0 to 300V DC) to power up the relay under test during bench testing or when substation auxiliary DC batteries are disconnected.
Q: How do you protect the test instrument against accidental back-feed from substation batteries?
A: All voltage and current output channels feature optical isolation, reverse-polarity protection, and automatic electronic trip-out circuits that isolate the internal amplifiers if an external voltage is inadvertently back-fed.
Q: Are the generated test reports directly compatible with utility asset management systems?
A: Yes. Test results, vector diagrams, and pass-or-fail criteria are saved in structured data files (such as PDF or XML format) via USB interface for seamless integration into utility maintenance databases.
Q: What is the advantage of automated test templates in relay calibration?
A: Automated templates eliminate human error by executing pre-configured test sequences (such as pickup time, characteristic curves, and harmonic blocking) and automatically comparing results against pre-set relay manufacturer thresholds.
Q: Do these units require external computers to operate in the field?
A: No. Units feature high-brightness daylight-readable touchscreens and embedded operating systems, allowing field technicians to run complete manual and pre-scripted test sequences directly from the front panel.
As one of the most experienced secondary circuit testing equipment manufacturers in China, we offer a wide range of products with superior quality. Please feel free to wholesale bulk durable secondary circuit testing equipment from our factory. For price consultation, contact us.
