Yuchai Diesel Generator Megohmmeter Usage Guide

1.Four Key Notes for Using Yuchai Diesel Generator Megohmmeter

①Handle the megohmmeter with care, avoiding severe or prolonged vibration or flipping to prevent damage to the pointer shaft tip or bearings, which could affect measurement sensitivity.

②When the pointer reaches "0", stop rotating the generator handle immediately to prevent damage to internal coils.

③After measurement, immediately discharge the tested object. Never touch measurement parts or disconnect wires while the handle is rotating or the object is still charged to prevent electric shock.

④ Store the megohmmeter in a dry cabinet when not in use. Avoid extreme temperatures, humidity,bad environments, or exposure to corrosive acidic/alkaline air/vapors that could cause moisture damage, mold, rust, or corrosion to internal components.

2.Megohmmeter Measurement Methods and Requirements

(1) Motor Status During Testing: Measure insulation resistance of motor windings under both actual cold and hot conditions. For inspection tests, cold condition measurement alone is sufficient.

(2)Measurement Methods: For separate windings (stator windings, excitation windings, reactors, current transformers, etc.) with external terminals, measure insulation resistance between each winding and ground, and between windings. Non-tested windings must be reliably connected to ground. For internally connected windings, only measure insulation resistance to ground.

For hand-cranked megohmmeters, maintain 120r/min rotation speed and take readings after pointer stabilizes. After measurement, discharge windings to ground before disconnecting test leads.

Before operation, operators must read the instruction manuals for the generator set, diesel engine, generator, and controller thoroughly.

① Install grounding wire correctly with cross-sectional area not less than the motor output line and grounding resistance ≤50Ω.

② Check starting system functionality (including battery capacity for normal starting).

③ Verify cooling water level, additive type, and dosage in the water tank.

④ Check engine oil level and type in the diesel engine oil pan, and fuel level and type in the fuel tank.

⑤ Ensure all mechanical connections are secure.

⑥ For units stored long-term with severe moisture, check insulation resistance of generator and connected electrical circuits using a 500V megohmmeter. Minimum insulation resistance should be 0.5MΩ; otherwise, drying measures are required.

⑦ Regularly inspect, clean, or replace lubricating oil, fuel, and air filters according to regulations.

⑧ Verify electrical instruments are intact with pointers at correct positions.

⑨ Check circuit wiring for correctness and secure connections, with all switches in open position.

⑩ Ensure moving parts operate smoothly without friction or jamming.

⑪ Connect diesel engine fuel supply and return lines, and bleed air from the fuel system using the manual fuel pump.

Dingbo Power has advanced testing equipment, modern production technology, professional manufacturing technology, perfect quality management system, and strong technical research and development capabilities. It can provide 3KW～2500KW various specifications of ordinary, automatic, four protection, automatic switching, low noise and mobile generator sets, high quality and low energy consumption to meet the diverse power needs of customers, and can also meet users with different voltages and different frequencies. It is required to create a parallel power supply system for multiple units. If you are interested in our product or any question on generator, welcome to send email to [email protected].