The principle and connection method of temperature relay, and the wiring method of thermal relay

Principle: The temperature control switch of the temperature sensing component is used as the bimetal sheet, when the electrical appliance is working normally, the bimetal sheet is in a free state, and the contact is in a closed and disconnected state, when the temperature reaches the operating temperature, the bimetal sheet is heated to produce internal stress and act quickly, open the closed contact, cut off the connected circuit, and thus play a role in temperature control. When the appliance cools down to the reset temperature, the contacts automatically close and open, returning to normal working condition.

1. When the contact temperature sensing installation is adopted, the metal cover should be close to the installation surface of the controlled instrument, and in order to ensure the temperature sensing effect, the temperature sensing surface should be coated with thermal conductive silicone grease or other thermal conductive medium with similar performance.

2. Do not collapse, loosen or deform the top of the cover during installation, so as not to affect the performance.

3. Do not let the liquid penetrate into the inside of the thermostat, do not crack the shell, and do not change the shape of the external terminal at will.

4. The product is used in a circuit with a current of no more than 5A, and the cross-section of the copper core should be selected as 05-1 2 wire connection; For use in circuits with a current of no more than 10A, the copper core cross-section should be selected for wire connection.

5. The products should be stored in a ventilated, clean, dry and non-corrosive warehouse with a relative humidity of less than 90% and an ambient temperature of less than 40.

The functions are the same, but the output terminals and parameters are different, and each has a wiring diagram, and the reason is the same, as long as you understand one and the other are similar.

That is, when the temperature is higher (or lower) than a certain temperature, the relay acts, whether it is connected to the normally open contact or normally closed depends on the actual application.

The punctuation is not standardized, the typing is wrong, and the average person really doesn't know what you're talking about?

The connection mode of the thermal relay: first connect the three wires L1, L2 and L3 in the air switch with the L1, L2 and L3 of the contactor contact; Then T1, T2, T3 of the contactor are connected with each other with the inlet of the three main contacts on the thermal relay; Finally, the outlet ports of the three main contacts are connected to the three-phase windings U, V, and W of the motor.

Auxiliary contacts, usually one normally open (NO) and one normally closed (NC) contacts. It is used in the control loop of the motor starter.

When the motor is overloaded, the current input to the motor will exceed the rated current of the motor, and the thermal element in the thermal relay will heat up due to the excessive current flowing through. Causes bending. The output contacts are switched by the internal mechanical structure.

To achieve the purpose of outputting an "overload" signal.

The "NC" contact set of the auxiliary contact can be connected in series in the power supply line of the control circuit (in series with the "stop" button), and once the motor is overloaded, the "NC" contact of the auxiliary contact will cut off the power supply to the control loop and stop the motor from running.

The "no" contact group of the auxiliary contact can be connected to an alarm device (e.g. alarm indicator), and once the motor stops running due to overload, the reason for the motor to stop is given - "overload".

Thermal concise relaysThe operator is to stop the law firstAir switchThe three lines of L1, L2, and L3 are withContactorsL1, L2, and L3 of the contacts are connected to each other. Then T1, T2, T3 of the contactor are connected with each other with the inlet of the three main contacts on the thermal relay; Finally, the outlet ports of the three main contacts are connected to the three-phase windings U, V, and W of the motor.

In the process of using the relay, the user must operate in strict accordance with the instructions of the relay, and its parameters must be controlled within the standard range.

In fact, the rated load is only a reference value, and when it is used, it will change due to various environmental factors and load performance. Therefore, it is recommended to confirm in advance for actual use. When the relay is in use, in order to ensure the performance of the product, you must be careful not to drop it on the floor, or make it encounter a strong impact.

If there is really a problem with the drop of the liter, it is recommended that it is best not to use it again to prevent danger.

The working wax principle and wiring method of the thermostat are as follows:

1. The wiring principle of valveless fan coil unit.

Wiring according to the diagram, Line 1 is connected to the zero line, Line 2 is connected to the live line, Line 3 is connected to the high-end, Line 4 is connected to the mid-range, and Line 5 is connected to the low gear. Insert each wire into the port and tighten it clockwise with a screwdriver.

2. The wiring principle of the fan coil unit of the two-wire valve.

Wiring according to the diagram, Line 1 is connected to the neutral line, Line 2 is connected to the live line, Line 3 is connected to the high-end, Line 4 is connected to the mid-range, Line 5 is connected to the low gear, and Line 6 is connected to the opening valve. Insert each wire into the port and tighten it clockwise with a screwdriver.

3. The wiring principle of the three-wire valve fan coil unit.

According to the diagram, Line 1 is connected to the zero line, Line 2 is connected to the live line, Line 3 is connected to the high-end, Line 4 is connected to the mid-range, Line 5 is connected to the resist, Line 6 is connected to the opening valve, and Line 7 is connected to the closing valve. Insert each wire into the port and tighten it clockwise with a screwdriver.

Thermostat Introduction:

Thermostat refers to a series of automatic control components that are physically deformed inside the switch according to the temperature change of the working environment, resulting in some special effects and on-off or disconnection actions. It is also called a temperature control switch, a temperature protector, and a temperature controller, referred to as a thermostat. Or the temperature is transmitted to the temperature controller through the temperature protector, and the temperature controller issues a switch command.

Its working principle is to automatically sample and monitor the ambient temperature through the temperature sensor, and when the ambient temperature is higher than the control set value, the control circuit is started, and the control difference can be set. If the temperature is still rising, when it rises to the set overrun alarm temperature point, the overrun alarm function will be activated, which is mainly used in various high and low voltage switchgears, dry-type transformers and other fields used in the power sector.

Wiring diagram and principle of thermostat switch:

The wiring of the thermostat, the following is the structure diagram of the thermostat terminal.

9 and 10 thermostat power input terminal, connected to 220 volt alternating current, 12 and 13, 1 and 2, thermostat alarm output circuit, series in the alarm circuit or indicator circuit, 14, 15, 16 relay output terminal, connected to relay coil.

Control the temperature control circuit to work or stop, 3 and 4 are the output end of the solid state relay, connected to the input end of the solid state relay, 6, 7, 8, three terminals, connected to the thermal resistance, 7 and 8 connected to the thermal resistance of each other short two wires, the other one is connected to the 6th terminal.

Electric fan heat dissipation and temperature control circuit:

220 volt alternating current through the leakage circuit breaker, connected to the thermostat power input terminal phase and in, in the zero wire, phase connected live wire, in the total, high connected to the electric fan, live wire directly connected to the electric fan, the sum high is a pair of normally closed contacts, only the thermocouple detected by the ambient temperature is lower than the set temperature of the thermostat when it is disconnected, the ambient temperature is higher than the set temperature of the thermostat, the high is in a closed state.

Action process: the leakage circuit breaker is closed, the live wire is connected with the electric fan, the zero line is connected to the total through the middle line, when the ambient temperature is higher than the set temperature, the total closing height is closed, the zero line and the electric fan are connected, the electric fan runs to cool down, when the ambient temperature is lower than the set temperature, the sum high is disconnected, and the electric fan stops running.

The working principle of thermal relay is to use the thermal effect of electric current to push the contacts of the contactor, so as to achieve the purpose of protecting the electrical appliance.

Thermal relays are mainly used to control the heating state of electrical equipment caused by overload protection, phase failure protection, current imbalance and other reasons of the motor.

Its working principle is to use the thermal effect of the current to deform the bimetal sheet with different expansion coefficients, and when the deformation reaches a certain distance, it will push the connecting rod to move and disconnect the control circuit, so that the contactor will lose power and the main circuit will be disconnected, so as to realize the overload protection of the motor.

Thermal relay model specification meaning

Thermal relays are mainly composed of thermal elements, bimetal sheets, and contacts.

Its working principle is based on the thermal effect of electric current, which deforms due to heat as it passes through it, eventually pushing the bimetal to act, thus closing or disconnecting the contacts.

The model number of a thermal relay usually consists of letters and numbers, such as "JR16-20 3D", where "JR" stands for thermal relay, "16" stands for design serial number, "20" stands for basic current (A), and "3D" stands for derived type.

Thermal relay application scenarios

Thermal relays are mainly used to protect inductive loads such as motors and transformers, as well as various electronic circuits.

In motor control circuits, thermal relays can be used in conjunction with contactors to provide overload protection for the motor. At the same time, thermal relays can also be used to protect circuits against faults such as short circuits and overcurrents.

A thermal relay is a kind of relay that generates heat through the heating element and bends the detection element to promote the action of the mechanism. Due to the heating inertia of the heating element in the thermal relay, instantaneous overload protection and short-circuit protection cannot be done in the circuit. It is mainly used for the overload protection of the motor, the protection of phase failure protection and the protection of three-phase current unbalanced operation and the control of the state of other electrical equipment.

The principle of thermal relay is that the current increases and heats up, the steel sheet inside the relay is deformed, and the opening or closing point on the relay is touched to control the electrical circuit. Plays a protective role.

Sharing of basic knowledge of electricians.

1. Thermal relay.

2. a contactor.

The main contact is connected with the main contact of the thermal relay, and the auxiliary contact of the thermal relay can be connected in series with the auxiliary contact of the relay or directly connected to the power supply of the control loop to protect the main circuit. Take the three-phase contactor and the three-phase thermal relay as an example, the three main wiring of the relay are connected to the lower outlet of the three-phase contactor.

3. Usually the thermal relay is connected to the bottom of the contactor, that is, the main circuit is the circuit breaker-contactor-thermal relay, and the normally closed auxiliary contact of the thermal relay is connected in series in the contactor coil circuit, so as to disconnect the contactor when the thermal relay acts.

The working principle and function of the thermal relay:When the motor is overloaded, the current flowing through the heating element exceeds the setting current of the thermal relay nucleus, the heating of the thermal element increases, the temperature rises, the bimetal sheet is heated and bent, and the push plate is pushed, so that the normally closed contact action is broken and opened, and the control circuit is disconnected so that the main circuit is also disconnected, which plays the role of overload protection.

Thermal relay structureTemperature sensing element: It consists of two resistance wires on bimetal sheets with different expansion coefficients. There is a difference between the main bimetal sheet and the compensating metal sheet.

Contact system: It is composed of normally closed contacts, normally open contacts and leaf springs.

Actuator: It is composed of a guide plate, a linkage system, etc.

Reset device: It consists of a manual reset button and a reset adjustment screw.

Current setting mechanism: It is composed of a current regulating cam and a compression spring.

Electrician Knowledge: What is Contactor Jogging? How to wire a thermal relay? Explanation of wiring steps.

The motor is easy to burn out when overloaded for a long time, and it will play a protective role with thermal relay protection.

Thermal relay is connected to the contactor on the left and the motor on the right, and the normally closed contact of the thermal relay is connected to the contactor coil circuit.