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For every electrical device, the basic prerequisite is a proper overcurrent safety of conductors and equipment. Overcurrent is a situation in which the current in amperes exceeds the measured current of equipment or conductors due to overload, ground failure, or short circuit.
An overcurrent protection device safeguards the circuits by opening the system when the current exceeds a value that can cause a rapid temperature rise in the conductors. Most overcurrent protection devices respond to both current values of short-circuit or ground-fault and overload conditions. It is crucial to personal and industrial safety and security from a variety of dangerous conditions that may result from the ignition of material due to inadequate defense against overload or short circuit. Besides, overcurrent protection devices shield against explosive ignition and flash hazards caused by insufficient voltage-rated or unsuitable devices.
Overcurrent Protection Relays
Overcurrent protection relays only work when the current value is higher than the relay setting time. It prevents power system equipment from the faulty current.
Depending upon its time of operation, overcurrent protection relays are divided into the following categories:
- Instantaneous Overcurrent Relay
- Definite Time Overcurrent Relay
- Inverse Time Overcurrent Relay
Usually, such devices are used in main service disconnects, in electrical network feeders and branch circuits for residential, businesses, institutional, and industrial premises.
Here are three ways to optimize your overcurrent protection:
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Protection Relays for Standard Use
Protection relays are switchgear devices that detect the faults and start the circuit breaker operation to isolate the faulty element from the remaining system. These overcurrent protection devices are compact and self-contained, which can detect irregular conditions. Protection relays for standard use consist of one base unit, a current and voltage connector, a conductor, one operating language, one application, an optional module, and core balance CT.
Once the protection relay detects the fault, it closes the breaker’s trip circuit. It triggers the breaker to open and defective circuit to disconnect.
Some of the best overcurrent protection relays which you can use for optimizing your overcurrent protection must have:
- Speed
- Sensitivity
- Reliability
- Simplicity
- Economy
- Selectivity
These qualities help a protection relay perform its functions for standard use satisfactorily.
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Protection Relays for Complex Distribution System
Protection relays safeguard all medium and high-voltage applications from overcurrent to complex distance protection, giving you the safety and reliability, you need for operating confidently. Overcurrent protection can be used as a primary backup for the protection of phase overcurrent or an earth fault.
Instant, definite time, direction, and non-directional, IDMT (Inverse Definite Minimum Time Relay), are some of the overcurrent characteristics that are often used in complex distribution systems.
Relays for complex distribution system has many applications in motor, transformer and generator protection, substation incomers, and feeder protection.
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Feeder Management Relays
Feeder management relays offer an optimized system for full protection, control, and tracking of underground cables and overhead lines, including voltage transfer and transmission. These are microprocessor-based units designed for the control and primary security of distribution feeders as well as for controlling and safeguarding buses, transformers, and transmission lines.
Features and Benefits:
- Digital relay
- Simulation function
- Incorporates control, protection, and meeting
- Efficient power system management
- Multiple communication protocols and interfacing options
- Multi-lingual user interface
Relays for Optimizing Overcurrent Protection
The primary unit of overcurrent protection is an overcurrent relay that provides safety against faulty currents, thereby saving your equipment and system. When you combine earth fault and overcurrent protection, the unit comprehensively safeguards all voltage applications.
Overcurrent protection is primarily used as primary protection in extra-high and high voltage networks, which is often used as a backup for power transformers in medium networks. The choice of relays entirely depends on your need for overcurrent protection optimization after all!