Checking and Repairing the Faults of Electric Drive Control Circuit by Voltage Measurement
1. The basic principle of voltage measurement method
The voltage measurement method is to use a multimeter to detect the working voltage in the circuit, and compare the measured result with the normal value in order to determine whether the circuit is working normally.
When the circuit is working normally, the operating voltage of each point in the circuit has a relatively stable normal value or a dynamic range. If there is a short-circuit fault, an open-circuit fault or a change in the performance parameters of the components in the circuit, the working voltage in the circuit will also change accordingly. Therefore, the voltage measurement method can detect whether the working voltage of some key points in the circuit is present or not, whether it is too large or too small, and whether the dynamic change is normal, and then analyze according to different fault phenomena and the working principle of the circuit to find out cause of failure.
2. Basic method of voltage measurement
The power supply is a necessary condition for the normal operation of the circuit, so when the circuit fails, the power supply part should be detected first. If the power supply voltage is abnormal, focus on checking the power supply circuit and load circuit for open or short circuit faults. Under normal circumstances, if there is an open circuit fault in the power supply, such as a blown fuse, the power supply will have no voltage output; if the load has a short circuit fault, the power supply voltage will drop.
1) When using the voltage measurement method to detect the circuit, it is necessary to understand the situation of the measured circuit and the range of the measured voltage, and then reasonably select the gear of the multimeter according to the actual situation to avoid burning the multimeter.
(2) Before measurement, it is necessary to distinguish whether the measured voltage is AC or DC, and ensure that the red test lead of the multimeter is connected to the test point with high potential, and the black test lead is connected to the test point with low potential, so as to prevent the multimeter from being damaged due to reverse bias of the pointer.
(3) Pay attention to prevent electric shock when using the voltage measurement method. During the measurement process, the human body should not touch the metal part of the test lead. During the specific operation, generally fix the black test lead, and then use one hand to hold the red test lead for measurement.
