Modern cable nine fault maintenance water thermometer electroacupuncture hit the head, the actual water temperature is not hot, what is the situation?

1. Water thermometer: used to indicate the temperature of cooling water inside the engine, which is an important indicator of whether the engine cooling system works normally.

2. What do you think of the water thermometer?

The water temperature from C-H, C means 60 degrees. As long as the pointer of the water thermometer reaches C, the water temperature has reached 60 degrees. H The temperature indicated by the red grid is 1 10 degrees. It is recommended to always keep the pointer in the middle position. When the pointer enters the red area, the water temperature is too high. If the water temperature is too high for a long time, "boiling" will occur, that is, the engine coolant will boil, which will cause the water tank to burst and the engine to overheat and be damaged.

3. Working principle

The negative temperature coefficient is installed in the sensor, and its resistance will decrease with the increase of temperature.

When the power switch is turned on, the current is divided into two paths (one path flows through the thermistor1; The other path flows through the coil L 1 )→ grounding → negative battery to form a loop.

When the water temperature is low, the resistance of the thermistor in the sensor is large, and the current flowing through the coil L 1 is similar to L2. However, due to the large number of turns of L 1, the generated magnetic field is strong, and the armature 3 with pointer will deflect to the left, so that the hands point to the low temperature scale. With the increase of water temperature, the resistance of thermistor decreases and the shunt effect increases. The current flowing through L 1 decreases, the magnetic field force weakens, the armature deflects to the right, and the pointer points to the high temperature scale.

4. Check the thermometer

When checking the electromagnetic temperature sensor and water temperature indicator, you can remove the wiring on the sensor and measure the resistance between the input end of the sensor and the ground. If the resistance of thermistor is about100Ω at room temperature, the sensor is good. In addition, a resistor with a resistance of 80-100Ω is used to directly ground the sensor. When the power is turned on, if the pointer of the water temperature indicator is between 60 and 70, it means that the water temperature indicator is good.