benlong 
MCCB manual magnetic trip test bench
Custom MCCB manual magnetic trip test bench for 125A/250A frames (custom up to 1600A). Programmable 5‑10× In current, ±1ms timing, pass/fail indication. Non‑standard designs available for larger frames, 4‑pole simultaneous testing, and auxiliary contact verification.
Custom MCCB Manual Instantaneous Magnetic Trip Test Bench
This MCCB (Molded Case Circuit Breaker) magnetic trip test bench provides accurate and reliable verification of instantaneous or magnetic trip performance for molded case circuit breakers. The test bench was designed by engineers specifically for use by professional maintenance and quality assurance teams, and will accept both 125A and 250A framed breakers with no additional adapaters required for testing. The stability of the current output, ease of operation, and fast measuring speed produce consistent and repeatable results when testing molded case circuit breakers operating under different conditions. The robust design and superior safety features of this test bench make it an ideal choice for laboratory and field testing.
A programmable power supply has the ability to produce high current (up to 10 times its rating) to check instantaneous trip time.
Standard delivery: 30-45 days | Non‑standard custom: 60-90 days | Accuracy: ±5% of test current
What is an MCCB Manual Magnetic Trip Test Bench?
A MCCB manual magnetic trip test bench is a special type of equipment designed to perform tests that check the instantaneous (short-circuit) protection of molded case circuit breakers. Unlike thermal testing, which tests overload protection through a specified range of currents (1.05 – 1.45× In), magnetic testing applies high current (in the range of 5-10× the rated current) to ensure immediate tripping of a circuit breaker (less than 1 millisecond) when short-circuited.
To perform a test using an MCCB manual magnetic trip test bench, the MCCB must be manually loaded into or unloaded from the bench before testing can occur. The bench will automatically create the test current when the MCCB is connected for testing, along with measuring the time of the trip and indicating pass/fail results.
The MCCB manual magnetic trip Test Bench is very important for routine quality assurance of manufactured circuit breakers, inspection after the receipt of MCCBs at the user’s premises, and maintaining MCCBs after being installed in low-voltage electrical distribution systems.
The test bench’s base model accommodates 125A and 250A frame circuit breakers. Additionally, custom models of the test bench can be ordered to accommodate circuit breakers greater than 250A (up to 1600A) and provide additional pole configurations or auxiliary contact verification capabilities.
No adapter change required between these two common frame sizes.
5×, 7.5×, 10× rated current (or custom multipliers) for B/C/D curves.
±1ms accuracy, digital display, automatic pass/fail judgment.
Tailored to your MCCB rating (up to 1600A), pole count, and special test requirements.
Test Features & Operation Process
Technical Specifications
| Supported MCCB frames (standard) | 125A, 250A (no adapter change) |
|---|---|
| Custom frame size range | Up to 1600A (tooling and current source customization required) |
| Pole configurations | 1P, 2P, 3P, 4P (test all poles simultaneously or sequentially) |
| Test current multipliers | Programmable: 5×, 7.5×, 10× In (or custom values via HMI) |
| Maximum test current | Up to 20,000A (depending on frame size) |
| Timing measurement range | 0 – 999ms, accuracy ±1ms |
| Display | Digital trip time, pass/fail LED, test count |
| Control interface | PLC + HMI (touch screen) with recipe storage for different MCCB types |
| Data output | CSV / USB export; optional MES integration via Ethernet |
| Power supply | 380V ±10% 50Hz | Three‑phase |
Core Technical Advantages (Custom Non‑Standard Design)
Wide frame compatibility
Standard bench covers 125A and 250A with quick‑change clamps. For larger frames (400A–1600A), we design custom fixturing and upgrade the current source accordingly.
Accurate current regulation
Closed‑loop thyristor control ensures stable test current regardless of line voltage fluctuations – critical for repeatable magnetic trip tests.
Operator‑safe high‑current handling
Enclosed test chamber with interlock, emergency stop, and remote start prevents accidental contact during high‑current injection.
Expandable to auxiliary contact test
Optional module can verify the state change of auxiliary contacts (NO/NC) during tripping – useful for MCCBs used in motor control centers.
Customer Success Story (Custom Non‑Standard Design)
A significant manufacturer of switchgear required its new MCCB’s to be tested for magnetic trip consistency during production, with current ratings of 630A (4-pole). The current bench was limited to testing MCCB frames with current ratings up to 250A, so Benlong created a customized manual magnetic trip test bench that included.
This solution reduced testing time by 70% and eliminated false fails resulting from inconsistent application of clamping pressure. It was self-funding after 8 months due to improved first-pass yields and reduced rework.
Applications and Lab Integration
Standard Delivery and Commissioning (Custom Engineering)
Request a Custom MCCB Magnetic Trip Bench Quote
Send us your MCCB frame sizes, rated current & test volume to get a recommended configuration from our engineers (current source ratings/pole count/data logging) that is compliant with IEC 60947-2.
WhatsApp: +86 150 5837 0007 | Email: xsb@benlongkj.cn | English & Chinese support
Why Choose Benlong for MCCB Test Benches?
- 15+ years designing magnetic trip test equipment for MCCB manufacturers
- Custom current sources up to 20,000A for large frames
- ±5% current accuracy, ±1ms timing, closed‑loop regulation
- Rugged, operator‑safe design with interlocked test chamber
- Global service and spare parts support
Typical Custom Bench Includes
Thyristor-controlled high current sources, a digital timer (± 1 ms), an HMI touch screen, data logging (CSV export), a calibration certificate, and a 1-year warranty are all included in the programmable current controller along with test leads/quick-connect clamps rated for 125A / 250A and a safety enclosure with an interlock.
Frequently Asked Questions
Magnetic trip testing under load conditions by applying a high current (5-10 times In) to check for tripping of the circuit breaker during a short-circuit condition and will verify the breaker will trip within milliseconds. Thermal trip testing will use a moderate overload (1.05-1.45 times In) and verify the trip time for the circuit breaker with test times of seconds or minutes. Our test bench will be used exclusively for magnetic trip testing.
Absolutely. The standard bench is available with quick-adjust clamps for 250A and also for 125A frame terminals. There are no extra adapters required to accomplish this. We can manufacture custom clamps for different frame sizes upon request.
The integrated electronic timer with +/- 1ms of accuracy provides enough precision to check instantaneous trip times that range from approximately 10 to 50 milliseconds when using MCCBs.
Yes, the test chamber is a complete enclosure that has an interlock to shut down the electrical supply source when the chamber access door is opened. There is also a remote start/stop button as well as an emergency stop button.
It is possible to log test results (date and time, type of MCCB, test current, trip time, pass/fail) to either a USB drive or directly to a PC through Ethernet (optional MES interface).
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