Static relay

In electrical systems, a static relay is a type of relay, an electrically operated switch, that has no moving parts. Static relays are contrasted with electromechanical relays, which use moving parts to create a switching action.

1. What is a static relay in protection?
2. What is static relay and its advantages?
3. What is the difference between static and digital relay?
4. What are the three types of relays?
5. What is the purpose of a relay?
6. What is the advantage of static relay over electromagnetic relay?
7. Do relays need AC or DC?
8. Does relay works on AC or DC?
9. Which relay is used for protection?
10. What type of relays are used for protection?
11. What is static overcurrent relay?
12. Which relay is mostly used?

What is a static relay in protection?

In a protection relay, the term 'static' refers to the absence of moving parts to create the relay characteristic. Introduction of static relays began in the early 1960's. Their design is based on the use of analogue electronic devices instead of coils and magnets to create the relay characteristic.

What is static relay and its advantages?

The static relay gives the quick response, long life, high reliability and accuracy and it is shockproof. The reset time of the relay is very less. It does not have any thermal storage problems. The relay amplifies the input signal which increases their sensitivity.

What is the difference between static and digital relay?

The output energizes the trip coil only when relay operates. In a static relay the measurement is carried out by static circuits consisting of comparators, level detectors, filters etc., while in a conventional electromagnetic relay it is done by comparing operating torque or restraining torque.

What are the three types of relays?

The three main types of relays are electromechanical, solid-state, and reed.

What is the purpose of a relay?

The relay permits a small amount of electrical current to control high current loads. When voltage is supplied to the coil, small current passes through the coil, resulting in a larger amount of current passing through the contacts to control the electrical load.

What is the advantage of static relay over electromagnetic relay?

As there are no rotating parts involved in the construction of static relays, these relays will give a faster response than electromagnetic relays. And also there are no frictional losses the power required for the static relays is less.

Do relays need AC or DC?

The operating voltage of a relay is generally in DC. Small signal relays and low voltage power relays are usually in DC, but mains control relays and contactors quite frequently have AC coils. The rest of the terminals of a relay are used to connect either a AC(generally 50/60Hz) or DC circuit.

Does relay works on AC or DC?

Just as it is impractical to operate a DC relay from AC, it is likewise impractical to operate an AC relay from DC. However, in an emergency, an AC relay may be operated from DC—provided certain precautions are taken.

Which relay is used for protection?

Electromechanical relays

An electromechanical protective relay can typically manage a maximum of two performance parameters or protective functions. The more complex varieties of the electromechanical relays (that may function based on the changes in electric electromagnetic forces) may be available as well.

What type of relays are used for protection?

Types of protection relays are mainly based on their characteristic, logic, on actuating parameter and operation mechanism. Based on operation mechanism protection relay can be categorized as electromagnetic relay, static relay and mechanical relay.

What is static overcurrent relay?

The overcurrent relays are used to detect faults in the distribution system. If the line is fed from both ends i.e. ring main system, these relays are used along with directional relays. These static overcurrent relays have the following advantages over electromagnetic relays.

Which relay is mostly used?

Electromagnetic relay

Electromagnetic relay is the simplest, oldest and most widely used relay. Its basic components are coils, magnetic cores, armatures, springs and contacts. The magnetic system is used to convert the input current into the mechanical power required for contact closure.