CKJ1140 Contactor Troubleshooting Five Step Method: Practical Guide for Coal Mine Scenarios

2025-07-11 15:03:38

In response to high-frequency faults of CKJ series contactors in coal mines, such as coil burnout, contact fusion welding, and mechanical jamming, combined with mining equipment operation and maintenance standards and fault cases, this article systematically outlines a five step standardized troubleshooting process, covering key links such as power outage detection, mechanism adjustment, and preventive maintenance, to help quickly restore safe equipment operation.

1、 Power outage safety detection: Lock the source of the fault (completed within 30 minutes)

Core steps:

1. Insulation resistance test:

-Use a 2500V megohmmeter to shake test the two ends of the main contact (standard: insulation value ≥ 2500M Ω after 1 minute). If it drops to<10M Ω within 

10 seconds, it is determined that the vacuum arc extinguishing chamber has failed (accounting for more than 70% of the faults).   

2. Coil on/off detection:

-Disconnect the control wire and measure the coil resistance with a multimeter: the normal value of the AC36V coil is about 160 Ω± 10%. If the resistance is ∞ (open circuit) or ＜ 100 Ω (inter turn short circuit), it needs to be replaced.   

3. Control voltage verification:

-No load test control Terminal voltage: If it is lower than AC30V (rated 85%), it will cause unreliable suction.   

2、 Deep processing of contact system: from dust cleaning to parameter calibration

Contact failures account for more than 40% of coal mine contactor failures, and should be executed in sequence:

1. Surface treatment:

-Polish the oxide layer with fine sandpaper (600 grit) and clean the metal particles with alcohol (file trimming is strictly prohibited to avoid damaging the flatness).   

2. Pressure and overtravel adjustment:

Insufficient pressure can easily lead to contact fusion welding, while excessive pressure can cause difficulty in suction.   

3. Vacuum degree retest:

-After repair, conduct a power frequency withstand voltage test on the main contact (AC8kV/1min without flashover).   

3、 Mechanical mechanism jamming treatment: lubrication and calibration (key explosion-proof requirements)

Coal mine vibration and coal dust can easily cause the mechanism to jam, which can be solved in three steps:

1. Disassembly and cleaning:

-Remove the magnetic yoke and clean the oil and rust on the pole surface of the iron core with industrial gasoline (note: the E-type iron core needs to be checked to remove magnetic air gap ≥ 0.2mm).   

2. Axis calibration:

-Check the bending degree of the shaft (≤ 0.1mm) and apply molybdenum disulfide high-temperature grease (suitable for -30 ℃~200 ℃).   

3. Bolt anti loosening:

-Threaded locking adhesive should be added to the fixing bolts of the suction iron core to prevent vibration loosening and magnetic leakage heating.   

>Lesson: The contactor of a coal mining machine in a certain mine got stuck, and the air gap increased to 1.5mm due to the loosening of the iron core bolts, causing the coil current to surge twice and burn out.

4、 Overall functional verification and preventive adjustment (eliminate rework)

Three verifications must be conducted before powering on:

1. Synchronization test:

-Close the three-phase contacts for different periods ≤ 0.5ms (detected by a laser rangefinder) to avoid current surges.   

2. Noise and temperature rise monitoring:

-The noise after suction is ≤ 35dB (at a distance of 1m), and the temperature rise of the iron core is ≤ 65K (infrared thermometer).   

Classic Fault Cases and Remedial Strategies

1. Contact fusion welding

-Phenomenon: The CKJ5-400 contact of a certain mining transport machine is welded dead, and the motor is blocked.   

-Root cause: Coal gangue jamming belt → locked rotor current 6 times rated value for 3 seconds.   

-Improvement:

-Install an intelligent motor protector (JDB model) and set the locked rotor action time to ≤ 0.5s;

-The contact has been upgraded to silver nickel alloy material (with welding resistance increased to 300%).   

2. Frequent burning of coils

-Phenomenon: After replacement, run for 8 hours and burn again.   

-Root cause: The auxiliary contact spring is deformed, and the coil cannot switch to low resistance maintenance mode.   

-Improvement:

-Replace the reinforced auxiliary contact module;   

-Control circuit parallel RC absorption circuit (C=0.1 μ F, R=100 Ω) to suppress surges.   

Special warning for coal mine scenes

1. Explosion proof compliance:

-After maintenance, the IP54 protection level needs to be restored, and the compression of the sealing ring at the wiring port should be ≥ 30%.   

2. Adaptation to locked rotor conditions:

-For heavy-duty equipment such as transport planes and crushers, the selection of contactors should be upgraded to a higher current level (such as selecting 400A contactors for 250A loads).   

3. Maintenance cycle:

-In high operating frequency scenarios (>600 times/hour), the lubrication cycle is shortened to 15 days.   

>The value of the five step method: Following this process can reduce 90% of repeated failures. The core lies in ensuring vacuum degree and maintaining mechanical accuracy - in harsh environments of coal mines, preventive maintenance is far more cost-effective than fault repair.