Contactless contactor is a kind of solid-state switch. We often confuse solid-state relay with contactless contactor. The main core component of solid-state switch is thyristor, also known as thyristor, which is used to control the on-off of the line. Because there is no mechanical contact and the service life is longer, it is called contactless contactor. The electrical life of mechanical contacts is generally 654.38+ million times, and that of contactless contactors can reach 654.38+00 18 million times.

Here, I want to focus on the difference between solid-state relay and contactless contactor. Many beginners are confused. Old electricians say solid state, so novices often regard solid state as solid state relay. In fact, solid state, we mean solid state switch, a big category.

Solid-state relays are commonly used in resistive loads, and the instantaneous current is 1 times that of normal startup, so there is no need to consider the problem of circuit heat dissipation (mainly caused by voltage drop). Therefore, the solid-state relay we often see has no heat sink, and the internal circuit does not need to consider the heat dissipation problem too much. The picture below shows 40A three-phase solid-state relay. Due to the different design directions of the circuit, when it is used in the motor, it is necessary to add a heat sink and a fan to avoid the heat dissipation problem caused by frequent start-up of the circuit. When using this product, frequent startup should be avoided to prevent the product from overheating and burning the internal circuit. The switching frequency of the motor should not exceed 100 times/hour, and it is best to add a temperature control switch, and stop using it when the temperature rises.

Contactless contactors are mainly used for inductive loads such as motors, and the instantaneous starting current is six times that of normal operation, so the internal circuit design of this product often pays special attention to voltage drop and heat dissipation. The picture below shows a 75-amp contactless forward and reverse contactor, which can be turned on and off 45 times per minute with a motor as the load.

Essentially, contactless contactor and solid-state relay are just two different names for solid-state switches. The difference between them lies in the internal circuit design (dealing with voltage drop), the load attribute (instantaneous current surge) and the size of internal components. It is more economical to use solid-state relay for resistive load (thermocouple), and it is more convenient to use contactless contactor for inductive load (motor).

Many technical electricians will call contactless contactors solid-state relays, and they mainly judge them according to the core components. It actually makes sense. Some sellers and salesmen don't understand technology and confuse the difference between them. Generally, they are collectively referred to as solid-state switches. When purchasing, they must choose these two products according to the load attributes.

Welcome to pay attention to Baijia Electric Superman, teach basic electrician and PLC introduction. Your concern is my greatest support.