Temperature Gauge Electric Contact Bimetal Thermometer

Electric contact temperature gauge 

The working principle of the electrical contact thermometer is to use the temperature change to drive the contact to change. When it contacts or disconnects the upper and lower limit contacts, it causes the relay in the circuit to act, thereby realizing automatic control and alarm functions.
Specifically, the electric contact bimetal thermometer is a single-needle indicating thermometer that uses a bimetal sheet wound into a spiral tube shape to be fixed at one end, and the other free end is connected to a pointer, which rotates as the temperature changes, and drives the pointer to rotate to indicate the temperature. When the temperature of the measured medium changes, the thin shaft and steering transmission mechanism on the free end will drive the pointer and the moving contact to rotate. When the movable contact contacts or disconnects from the fixed contact (upper and lower limit contacts), the relay and contactor in the circuit system will act, thereby achieving the purpose of automatic control and alarm34.

In addition, electrical contact thermometers can be calibrated based on the relationship between temperature and potential difference, allowing the temperature to be calculated by measuring the potential difference1. Different electrical contact thermometers may have different specific working methods. For example, the electrical contact pressure thermometer measures temperature based on the changing relationship between the saturated vapor pressure and temperature of the evaporating liquid in a closed temperature measurement system.

There are several ways to wire an electrical contact thermometer, depending on the application and the required measurement accuracy. Here are several common wiring methods:

Two-wire method: This is the most basic connection method, just use two wires to connect the two ends of the thermometer. However, this method may be affected by factors such as wire resistance, resulting in limited measurement accuracy.

Three-wire method: In order to improve the measurement accuracy, the three-wire method can be used for connection. This method adds a wire to eliminate interference factors such as wiring resistance, and can more accurately measure the electromotive force of the thermocouple, thus improving the accuracy of temperature measurement.

Four-wire method: For applications requiring higher accuracy, the four-wire method is the best choice. The four-wire method uses two wires to carry the current and the other two wires to measure the electromotive force of the thermocouple.

Oil transformation contact thermometer wiring diagram: Oil transformation contact thermometer is used to monitor the oil temperature of the transformer. Its wiring includes power wiring, signal wiring and grounding wire. The power wires L (live wire) and N (neutral wire) are connected to the power input terminal of the thermometer respectively. The signal wire includes the normally open contact NO, the normally closed contact NC and the common terminal COM. The ground wire PE should be connected to the ground terminal of the device .

Electric contact pressure thermometer wiring: Take the WTQ-288 type as an example. When the temperature of the measured medium drops to the lower limit, the indicator needle (moving contact) is connected to the lower limit contact, 1 and 2 are connected, and the signal light turns on; when the temperature of the measured medium rises to the upper limit, the movable contact is connected to the upper limit contact, 2 and 3 are connected, and the alarm bell sounds .

Three-wire temperature sensor wiring method: First, accurately distinguish the signal wire, compensation wire and ground wire. It is better to use wires when wiring. The wires should be divided into three wires: red, yellow, and black. The red wire is the positive pole, the yellow wire is the negative pole, and the black wire is the ground wire. The signal wire (red wire) needs to be connected to the positive terminal of the receiver

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