Fault detection method of speed control system of Cummins generator set

Turn on the power switch of the control box of Cummins generator set. When there are two quick, crisp and small sounds, the speed control system is basically normal; If there is no sound, it may be that the speed control board has no output or the actuator is rusted and stuck.

(1) Fault detection of control board
When the power switch is on, measure the DC voltage of a23-a22 on the large base plate. If the voltage is higher than 12V, it indicates that the output of the control board is normal. If u = 0, measure the voltage at points B and C of the socket of the speed control board. If u > 12V, the control board is normal. Check whether the printed circuit of the large base plate is open; Otherwise, if the speed control board fails, replace the control board.

(2) Fault detection of actuator
The coil resistance of the actuator is 7-loq and the inductance is 120mh. It is insulated from the ground. The electrical condition can be judged by static measurement of various parameters; When it is difficult to judge the mechanical condition of the operating set, an external 12V direct power supply can be connected, which can be judged by the sound condition when it is on and off. When the card is blocked and rusted, the actuator can be removed with special tools for cleaning and grinding (metal abrasive is not allowed) for repair. When it cannot be repaired, it shall be replaced.
When the control board cannot control the normal output out of control, it is caused by oil leakage due to wear and increased clearance of the actuator. When the idle speed is set at n < 600r / min and the speed rises to 900-l700r / min, it is usually called no idle speed. When the set running state is n = l500r / rain, the actual speed is below l700r / min and the speed regulation is invalid, which is caused by the above reasons. Because the diesel generator set works at about l500r / rain, the idle speed has little effect, and the actuator can continue to be used; When the oil leakage is serious and the speed is too high, but when loading Lo% – L5%, the speed drop can reach the normal control state, and the actuator can also continue to be used; If the speed increases a lot until it stops due to overspeed protection, replace the actuator.

(3) Detection of speed sensor
When the signal of the speed sensor is too strong, the speed of the speed control system is unstable. When the signal is too weak and there is no signal, it is easy to control failure and cause overspeed. The coil resistance of the speed sensor is about 300 Ω, and the output voltage is 1.5-20vac during operation. Otherwise, the sensor shall be replaced in case of fault. Adjustment of speed signal strength of speed sensor: screw the sensor in, tighten the gear end of flywheel, then exit for 1 / 2-3 / 4 turn and lock it. At this time, the gap between the top of the sensor and the flywheel tooth tip is about 0.7mm-1.1mm. The spin in output voltage increases and the spin out output voltage decreases.

Post time: Jan-13-2022