In situations when several circuits need to be controlled by a single signal, an electrically operated switch, such as a relay, is essential for controlling an electrical circuit using a separate low-power signal. Relays were first employed as signal repeaters in long-distance telegraph lines. Later, they were widely used to accomplish logical functions in early computers and telephone exchanges. Relays come in a variety of forms, and each type is employed according to the situation. Thus, an overview of a protective relay, also known as a protection relay, dealing with applications is covered in this article.
What is a protective relay?
By definition, a protective relay is a switchgear device
that detects faults and initiates the circuit breaker operation to isolate the
problematic component of the system. Electrical values are measured by these
relays to determine abnormal circumferences of a circuit. Current, voltage,
phase angle, and frequency are examples of electrical quantities that might
alter during fault situations. An automatic device known as a protection relay
closes its contacts when it detects anomalies in an electrical circuit. By
completing the circuit breaker's trip coil circuit, the defective piece is
disconnected from the healthy circuit and the breaker trips.
How does a safety relay work?
Once a system failure has been identified, the device is
protected by a protective relay. The circuit breaker, or CB, receives the
tripping signal after the fault site has been identified. The two principles
that these relays operate on are electromagnetic attraction and electromagnetic
induction. The coil is drawn toward the electromagnet poles by an
electromagnetic attraction relay, which merely operates on both supplies, such
as AC and DC. These relays operate instantly and without delay, whereas the electromagnetic
induction relay just requires an AC power source and uses an induction motor to
produce torque. Thus, these are frequently employed in high-speed-based
switching operation applications as well as directional relays to safeguard the
power system.
Protective Relay Types
Protective relays are available in different types, which are
used based on requirements.
Overcurrent Relays
Overcurrent relays use the current to function. The current
may cause the overcurrent relays to activate. When the measurement and current
amount surpass the pickup value, this relay, which has a pickup value, turns
on.
Directional Relays
A certain direction of current flow activates these relays.
It may identify a difference between the reference and actuating currents.
Distance Relays
In addition to differentiating between faults within a
certain area and inside a separate element of the system, this distance relay
is used to distinguish between normal operating conditions and a fault.
Pilot Relays
To ascertain whether a problem is inside or outside the
protected line, the pilot relay is utilized. All of the circuit breakers (CBs)
at the line terminals trip at full speed if the fault is internal to the
protected line.
Differential Relays
Simply comparing the primary difference between the entering
and exiting current magnitudes and values is how a differential protection
relay operates. The breaker circuit (CB) may be activated, and the system may be
separated if the difference exceeds the pickup value.
Electromechanical Relays
Although they were the first relays, electromechanical
relays are still used in many applications today. After receiving a control
signal, this relay merely uses the magnetic field produced by an
electromagnetic coil.
Protection and Relay
Advantages of Protective Relay
- Electrical protection is provided by a protection relay.
- The protection relay greatly minimizes or completely prevents equipment damage by identifying issues early on.
- The primary function of this relay device is to trip a circuit breaker (CB) as soon as a problem is detected.
- This relay functions similarly to a detecting device, identifying problems, determining their location, and then sending a tripping signal to the circuit breaker.
- This switchgear device detects problems and activates the circuit breaker to remove the problematic component from the system.
- These are highly beneficial for sophisticated distance protection, overcurrent protection, and protection against high and medium voltages.
Conclusion
Protective relays are essential defenders of industrial safety and electrical power networks. In order to protect equipment and system stability, a protective relay makes sure that problems are quickly identified and isolated. By stopping dangerous machine operations, a safety relay, on the other hand, puts human safety first. The foundation of electrical safety is made up of protection and relay systems, which combine precision, dependability, and technology to safeguard people, property, and the energy supply. Relays are getting smarter, faster, and more connected with digital networks as technology develops, making power systems safer and more effective globally. Protective relays essentially continue to be the unseen defenders of electricity, always observing, identifying, and responding to guarantee that power is delivered securely to the most critical locations.
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