What is the difference between a relay and a contactor?

As an electrical component for various state or parameter judgment and logic operation of the system, the relay mainly plays the role of signal conversion and transmission, and its contact capacity is small. Therefore, it is usually connected to the control circuit to react to the control signal, and is not directly connected to the main circuit with a certain load like the contactor, which is the fundamental difference between the relay and the contactor.

The contactor contact can withstand the load of a larger current, according to different models, from a few amperes to several hundred amperes (generally 9A 500A), which is mostly used for the control of AC three-phase motors, so it is mostly AC contactors, and the corresponding operating coils are also mostly AC, if the operating current is DC, it is necessary to pay attention to it when selecting the model.

The contact of the relay or miniature relay can be used to withstand a small current, generally about 5A, which is mostly used for signal transmission.

In other respects, the two are basically the same, and the principle is basically the same.

Contactors have arc extinguishing devices, while relays do not.

The function of the relay is to detect, transmit, convert or dispose of the signal, and the circuit current it turns on and off is generally small, and it is generally used in the control circuit to control weak signals. The contactor function is used to turn on or off the main circuit.

Relays are generally used in electrical control circuits to extend the contact capacity of miniature or miniature relays to drive larger loads. Contactors are used in (power) main circuits, and the main contacts can have interlocking contacts to indicate the opening and closing of the main contacts.

The contact method of the relay.

1. The two contacts are disconnected when the coil is not energized, and the two contacts are closed after being energized.

2. The two contacts are closed when the coil is not energized, and the two contacts are disconnected after the energizing is electrified.

3. The conversion type (Z type) is the contact group type. This type of contact group has a total of 3 contacts, i.e. a moving contact in the middle and a static contact at the top and bottom. When the coil is not energized, the moving contact and one of the static contacts are disconnected and the other is closed; After the coil is energized, the moving contact will move, so that the original disconnected is closed, and the original closed is disconnected, so as to achieve the purpose of conversion.

The key differentiator between a relay and a contactor is their sole purpose. Relays are typically used in low-voltage switching applications, while contactors are used in high-voltage switching applications.

The overall size of the relay is smaller compared to the contactor. Despite their small size, relays are heavier as compared to contactors.

The electromagnets used in relays are comparatively smaller in size than those used in contactors, so relays consume less power as compared to contactors.

Contactors are much more expensive than relays.

The presence of relays is suitable for control circuits for single-phase loads. However, contactors are present in the main circuits used for control and power applications of three-phase loads.

The load in the relay is designed to handle currents of about 10 A or less, while the load in the contactor can handle more than 10 A, up to or 50 A.

Relays are supplied with a rated voltage of up to 250 V, while contactors are rated at around 1000 V.

For the same application, relays provide faster switching speeds than contactors.

Relays are designed to control 2 or 3 loads, while contactors typically control 4 loads, and contactors offer load scalability up to or even 12 loads.

Contactors are said to provide better safety during operation than relays because safety components such as arc suppression systems and spring contacts are built into the contactor but are not present in relays.

In relays connected to overload, an overload connection is usually not provided, whereas in the case of a contactor, an overload connection does exist to handle excessive power consumption.

In relays, there is no opportunity to change the coils in them when needed, whereas most contactors support changing the coils when needed.

Relays support normally open or normally closed contacts depending on the condition, while contactors are typically designed to operate under normally open contacts.

Difference Between Contactor and Relay::

1. The essential difference between the relay and the contactor is that the load is different, the contactor with a large current capacity is the relay, and the difference is between the contactor used in the main circuit and the relay used in the control loop.

2. The function of the contactor is to turn on and break large current signals and drive power equipment such as motors;

3. The function of the relay is to convert the signal, and the interface between the equipment of different voltage levels to control the signal, the contact carrying capacity is generally small, and it is used to drive contactors and other electrical components.

When connecting the circuit, we generally install contactors, relays, air openings and other equipment, some people want to use contactors instead of relays, what is the difference between contactors and relays?

1. The definitions are different.

The contactor is an automatic switcher used to break the main current with load, which is generally installed in the main circuit and is used to control the load electrical appliances, for example, the contactor can control the switch of the motor, etc., it is suitable for frequent operation and long-distance control. Relays belong to electronic controllers, which are generally installed in the control loop and are used to regulate, protect, and convert circuits.

2. The contact is different.

The contactor contact is a surface contact, and the current that the contact can carry is large, and the general contact current is between more than ten amperes and hundreds of amperes, and multiple contacts can carry thousands of amperes in parallel. The relay contact belongs to the point contact, and the current that the contact can carry is small, generally about 5-10A, and the maximum is not more than 16A.

3. Arc extinguishing device.

The contactor has an arc extinguishing device, because the contactor current is large, and the contact current will be generated when it is contacted. The relay does not have an arc extinguishing device because the contact current of the relay is small, and no arcing is generated when contacted. If the relay is used to turn on and off the DC circuit, two normally open contacts are usually connected in series, and the arc can be extinguished quickly without arcing.

4. Functional role.

The contactor can be switched on and off circuits, and it has thermal stability and overload capacity, which relays generally do not have. The relay plays the role of signal relay, which can control the weak signal and break the short-circuit current. The contactor can only passively withstand the impact of the short-circuit current and will not break the short-circuit current.

Summary: What is the difference between contactors and relays, I will briefly introduce it to you here. I hope that after reading this article, you will be able to understand the difference between contactors and relays.

Contactors, mainly used for primary circuits, can pass larger currents (up to several hundred to more than a thousand A); The relay is used in the secondary circuit, and can only achieve various control functions through a small current (a few A to more than ten A).

Difference Between Contactor and Relay::

1. The role is different

The primary role of the relay is to detect, transmit, convert or dispose of the signal, and the circuit current it opens and breaks is generally small, and it is generally used in the control circuit to control weak signals.

The primary function of the contactor is to turn on or off the main circuit. The main circuit refers to whether a circuit works or not is marked by whether the circuit is turned on or not. The main circuit concept corresponds to the control circuit. Generally, the current passed through the main circuit is larger than that of the control circuit.

Contactors with large capacities are generally equipped with an arc extinguishing hood. The contact capacity of the relay generally does not exceed 5A, the contact capacity of the small relay is generally only 1A or 2A, and the contact capacity of the contactor is the smallest 9A; The contactor contacts generally have three pairs of main contacts (the main contacts are all normally open contacts), and there are several pairs of auxiliary contacts.

The contacts of the relay are generally not divided into main and auxiliary; The contacts of relays are sometimes set in pairs, that is, the normally open and normally closed contacts are combined, while the contactors are not set in pairs; Relays will be combined with other equipment for specific needs, such as time relays, counters, pressure relays, etc., which have additional functions, while contactors generally do not.

2.Contact opening and closing: In addition, the contactor is used to turn on or off the load with higher power, and is used in the (power) main circuit, and the main contact can have interlocking contacts to indicate the opening and closing of the main contact.

Relays are generally used in electrical control circuits to extend the contact capacity of miniature or small relays to drive larger loads. For example, the contacts of the relay can be used to turn on or off the coil of the contactor. Generally, relays have more opening and closing contacts, of course, relays can also complete some special functions through appropriate connection, such as logical operations.

3。The above two are similar: both drive the opening and closing of the contacts by controlling the electric or non-electric power of the coil to open or turn on the circuit. Attributed to electrical appliances with contacts. The control circuit of the coil is electrically isolated from the electrical circuit of the contact address.

Hello dear! We'll be happy to answer for you. The difference between a contactor and a relay A:

Electromagnetic relays and contactors, their working principle should be said to be the same. Sometimes the same device is used as a contactor in one circuit and as a relay in another circuit. How can you tell the difference?

The way to distinguish them is to look at their specific uses. The main function of the relay is to detect, transmit, convert or process the signal, and the circuit current it turns on and off is usually small, that is, it is generally used in the control circuit (as opposed to the "main circuit"). The main function of the contactor is to turn on or off the main circuit.

The so-called main circuit refers to whether a circuit works or not is marked by whether the circuit is turned on or not. The main circuit concept corresponds to the control circuit. Generally, the current passed through the main circuit is larger than that of the control circuit.

Therefore, as a friend on the first floor said, contactors with large capacity are generally equipped with an arc extinguishing cover (because a large current will produce an arc, and the arc extinguishing cover will burn out the contact if the arc extinguishing cover is not used). If the operating current of a main circuit is small, it is completely possible to use the electrical appliance usually used as a relay as a device to turn on and off the main circuit. The relay is used as a contactor.

However, if the working current of a main circuit is very large, so that the capacity of the contactor that uses the on-off main circuit is very large, the current to make such a contactor work is also very large, that is to say, the current flowing in its control circuit is very large, and it is difficult to turn on and off its control circuit with ordinary relays. At this time, an electrical appliance that was originally used as a contactor can be selected as the on/off of the control circuit, and the role of this contactor in this occasion is the relay.

1. The carrying capacity is different

Relays are generally classified to carry loads of 10A or less, while contactors will be used for loads greater than 10A.

2. The components are different.

The contactor is mainly composed of electromagnetic system, contact system, arc extinguishing system and other parts; Whereas, relays are mainly composed of coils, armatures, moving contacts and static contacts.

3. The role is different.

The primary role of relays is to detect, transmit, convert or dispose of land. The function of the contactor is to turn on or off the main circuit.

4. The working principle is different.

The working principle of the contactor is that when the contactor coil is energized, the coil current generates a magnetic field. Then the generated magnetic field will cause the static iron core to produce electromagnetic attraction to attract the moving core, and drive the AC contactor point to act, the normally closed contact is disconnected, the normally open contact is closed, and the two are linked.

When the relay is working, the electromagnet is energized, the armature is sucked into contact, and the working circuit is closed. When the electromagnet loses its magnetism when it is de-energized, the spring pulls the armature up and cuts off the working circuit.

The differences between contactors and relays include appearance, structure, function, doula application scenarios, control methods, costs, etc.

1. Appearance

Contactors are usually larger than relays and have a structure composed of electromagnets and contacts in appearance, and relays are usually smaller than contactors and have a structure composed of electromagnets and contacts in appearance.

2. Structure

Contactors typically include components such as electromagnets, contacts, connectors, and fixing plates, while relays typically include components such as electromagnets, contacts, moving irons, and fixing plates.

3. Function

Contactors are typically used for high-power, high-current load control, while relays are often used for low-current, low-power signal control.

4. Application scenarios

Contactors are usually used in high-power, high-load application scenarios, such as motors, resistance furnaces and other equipment in industrial production. Relays are usually used in electronic circuit control, automation equipment control, instrumentation and other fields.

5. Control mode

The contactor is usually controlled by manual, automatic and remote, while the relay is usually controlled by electrical signal.

6. Cost

Due to the relatively complex materials used and manufacturing processes used in contactors, their costs are usually higher. Relays, on the other hand, have relatively low costs due to their advantages of miniaturization and stable electrical performance.