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Application fields of relays
2020-01-10
Times：2120 
BackThe relay has a wide range of applications, and its environmental conditions and technical requirements vary widely. Even the different application occasions in the same application field have different requirements. The following can only catch the key points, give a few examples, and briefly explain. The key is to apply the knowledge described in the next section, and choose reasonably according to the specific requirements of the user.
1.Automotive field
The automotive industry is using relays more and more widely. The more common relays are: starter relays for starting motors, snubber relays, motor or generator open circuit relays, charging voltage and current adjustment relays, signal switching flash relays, light brightness control relays, air conditioning control relays, and sliding door automatic opening and closing controls Relay; glass window lift control relay. The power supply in cars now uses 12V, and the coil voltage is mostly designed to 12V. Because it is powered by a battery, the voltage is unstable; coupled with harsh environmental conditions, the suction voltage V≤60% VH (rated working voltage); the coil overvoltage is allowed to reach 1.5VH. The power consumption of the coil is large, generally 1.6 ~ 2W, and the temperature rise is high. The environmental requirements are quite harsh: the ambient temperature range is -40 ° C to 100 ° C; the relays used in the engine case must be able to withstand the damage of sand, dust, water, salt, and oil; vibration and shock are undoubtedly very harsh, and the impact strength is 100g , Shock stability up to 10g; vibration has 10 ~ 40HZ, double amplitude 1.27mm; 40 ~ 70Hz, 0.5g; 70 ~ 100Hz, 0.5mm (double amplitude); 100 ~ 500Hz, 10g and other levels.
2.Household appliances
(1) Air conditioner: The relay is mainly used to control the compressor motor, fan motor and cooling pump motor to perform related control functions. Household appliances compressor motors generally have 1 to 3 horsepower; fan motors and cooling pump motors have 1/4 to 2 horsepower. Due to the moment when the load starts, a large inrush current occurs, which is about 6 times the full load operating current. It takes a long time for the compressor motor to reach full speed, which poses a serious threat to the relay contacts. Therefore, it is required to leave a sufficient margin for the load capacity of the relay; it is required to eliminate the contact bounce when the relay is attracted as much as possible; and it is required to release the relay. Fast and minimize contact bounce. Safety requirements are strict and need to be certified by a safety certification body. Product environmental conditions: ambient temperature -40 to 55 ° C; relative humidity of 40 ° C, 95%; protection against rainwater infiltration; and protection against salt spray in coastal areas. Because weight and size are not important indicators, the relay design is required to be rugged and impact resistant.
(2) Household appliances: In this field, relays are used in washing machines, microwave ovens, electric heaters, etc. Relay contact load: The load can be as large as 220V, 5000W heater (or 1 horsepower motor), as small as driving small loads such as solenoids, other relay coils, and indicators. The expected life of the relay is 5 to 10 years. That is to say, the electrical life of the relay is required to reach 105 to 2 × 105 times. Ambient temperature: -40 to 55 ° C (microwave oven, electric heater requires 85 ° C); relative humidity 20% to 95%. Safety requirements are strict and must be confirmed by a safety certification body.
3.Industrial control relay
In industrial control, the main control functions are completed by universal AC relays. Relays are usually driven by push buttons or limit switches. Relay contacts can control solenoid valves, larger starter motors, and indicator lights. The voltage is generally 24VDC, 220VAC. The field of digital control has expanded the application of relays. Profiling milling and coordinate boring are operated by data programming. Signals are sent to the machine tool controller, memory unit and other logic elements to control 2 to 5 axes of coordinate servo motors. With this automatic control method, it is easy to control drilling machines, hexagon lathes, ordinary lathes and automatic profiling machines. The digital control system requires the relay to have the ability to adapt to low-level signals, medium sensitivity, fast action, and high switching reliability. The environmental conditions of industrial machinery installation must be considered. The operating industrial machinery and nearby equipment always transmit some shocks and vibrations to the control cabinet; there is also the possibility of splashing cutting coolant. Equipment manufacturers usually take certain protective measures for control components, but these adverse environmental conditions must still be considered when selecting and designing relays. Safety requirements are strict, with high requirements for electrical insulation, pressure resistance, and flame retardancy.
1.Automotive field
The automotive industry is using relays more and more widely. The more common relays are: starter relays for starting motors, snubber relays, motor or generator open circuit relays, charging voltage and current adjustment relays, signal switching flash relays, light brightness control relays, air conditioning control relays, and sliding door automatic opening and closing controls Relay; glass window lift control relay. The power supply in cars now uses 12V, and the coil voltage is mostly designed to 12V. Because it is powered by a battery, the voltage is unstable; coupled with harsh environmental conditions, the suction voltage V≤60% VH (rated working voltage); the coil overvoltage is allowed to reach 1.5VH. The power consumption of the coil is large, generally 1.6 ~ 2W, and the temperature rise is high. The environmental requirements are quite harsh: the ambient temperature range is -40 ° C to 100 ° C; the relays used in the engine case must be able to withstand the damage of sand, dust, water, salt, and oil; vibration and shock are undoubtedly very harsh, and the impact strength is 100g , Shock stability up to 10g; vibration has 10 ~ 40HZ, double amplitude 1.27mm; 40 ~ 70Hz, 0.5g; 70 ~ 100Hz, 0.5mm (double amplitude); 100 ~ 500Hz, 10g and other levels.
2.Household appliances
(1) Air conditioner: The relay is mainly used to control the compressor motor, fan motor and cooling pump motor to perform related control functions. Household appliances compressor motors generally have 1 to 3 horsepower; fan motors and cooling pump motors have 1/4 to 2 horsepower. Due to the moment when the load starts, a large inrush current occurs, which is about 6 times the full load operating current. It takes a long time for the compressor motor to reach full speed, which poses a serious threat to the relay contacts. Therefore, it is required to leave a sufficient margin for the load capacity of the relay; it is required to eliminate the contact bounce when the relay is attracted as much as possible; and it is required to release the relay. Fast and minimize contact bounce. Safety requirements are strict and need to be certified by a safety certification body. Product environmental conditions: ambient temperature -40 to 55 ° C; relative humidity of 40 ° C, 95%; protection against rainwater infiltration; and protection against salt spray in coastal areas. Because weight and size are not important indicators, the relay design is required to be rugged and impact resistant.
(2) Household appliances: In this field, relays are used in washing machines, microwave ovens, electric heaters, etc. Relay contact load: The load can be as large as 220V, 5000W heater (or 1 horsepower motor), as small as driving small loads such as solenoids, other relay coils, and indicators. The expected life of the relay is 5 to 10 years. That is to say, the electrical life of the relay is required to reach 105 to 2 × 105 times. Ambient temperature: -40 to 55 ° C (microwave oven, electric heater requires 85 ° C); relative humidity 20% to 95%. Safety requirements are strict and must be confirmed by a safety certification body.
3.Industrial control relay
In industrial control, the main control functions are completed by universal AC relays. Relays are usually driven by push buttons or limit switches. Relay contacts can control solenoid valves, larger starter motors, and indicator lights. The voltage is generally 24VDC, 220VAC. The field of digital control has expanded the application of relays. Profiling milling and coordinate boring are operated by data programming. Signals are sent to the machine tool controller, memory unit and other logic elements to control 2 to 5 axes of coordinate servo motors. With this automatic control method, it is easy to control drilling machines, hexagon lathes, ordinary lathes and automatic profiling machines. The digital control system requires the relay to have the ability to adapt to low-level signals, medium sensitivity, fast action, and high switching reliability. The environmental conditions of industrial machinery installation must be considered. The operating industrial machinery and nearby equipment always transmit some shocks and vibrations to the control cabinet; there is also the possibility of splashing cutting coolant. Equipment manufacturers usually take certain protective measures for control components, but these adverse environmental conditions must still be considered when selecting and designing relays. Safety requirements are strict, with high requirements for electrical insulation, pressure resistance, and flame retardancy.
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