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Protection Relays

Protection relays are essentially monitoring devices that keep a watchful eye over the electrical circuits and equipment, such as transformers, generators, and transmission lines. They detect abnormal conditions, like short-circuits or overloads, and take necessary actions to mitigate these problems. The primary action typically involves sending a signal to breakers to disconnect the faulty section from the rest of the system. This action prevents further damage, possible blackouts, or safety hazards.

The principle behind the operation of relays is based on the measurement of electrical quantities like current, voltage, frequency, and sometimes temperature. Depending on these measurements, a relay can determine whether the system is operating within safe parameters or not.

There are different types of protection relays, and they can be categorized based on their function, construction, or operating mechanism. For instance, there are distance relays that operate depending on the impedance between the relay location and the fault point, differential relays that function by comparing the difference between input and output electrical quantities, and overcurrent relays that respond to excessive currents.

Products

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$9066.28
Littelfuse SE-135-10 is a conformally coated relay unit with various relay contact configurations, including 1 Form A, 1 Form B, and 2 Form C. It offers both fail-safe and non fail-safe operation with IEEE device numbers 3GC, 50G, 50N, 51G, and 51N. Reset options include front-panel switch or remote N.O. contact, and it features standard harmonic filtering with a GF trip time of 0.10-2.5 seconds. Suitable for resistance grounded AC systems with a supply voltage of 24-48Vdc, the SE-135-10 offers auto/manual reset options and adjustable GF trip levels ranging from 0.50 to 12.5A. It includes a front-panel test button and standard CT loop monitoring.
$11674.93
Littelfuse SE-135-03 is a conformally coated relay with various relay contacts configurations. It operates in fail-safe or non-fail-safe mode and has IEEE Device Numbers 3GC, 50G, 50N, 51G, and 51N. It supports front-panel and remote N.O. contact reset types, has standard harmonic filtering, and latching/autoreset options. Its communication capabilities include Ethernet. The product has a range of supply voltage options for both AC and DC. It features a test button and standard CT loop monitoring.
$7537.37
Littelfuse SE-135-00 is a versatile relay with various configuration options including 1 Form A, 1 Form B, and 2 Form C contacts. It can operate in fail-safe or non-fail-safe mode, and offers front-panel or remote reset options. With standard harmonic filtering and resistance grounded AC system compatibility, it is designed to accurately trip at GF levels ranging from 0.50 to 12.5 A.
$9984.54
Littelfuse SE-134C-XGC-10 is a conformally coated relay device suitable for both 50Hz and 60Hz frequencies. It features relay contacts in 1 Form A (N.O.), 1 Form B (N.C.), and 2 Form C (N.O./N.C.) configurations, with fail-safe and non fail-safe operation options. Designed for resistance grounded AC systems, it has a wide supply voltage range of 24-48V DC and supports front-panel switch or remote N.O. contact reset. Other features include standard harmonic filtering, GF trip time ranging from 0.10 to 2.5 seconds, GF trip level from 0.50 to 12.5 amps, a front-panel test button, and standard CT loop monitoring.
$8320.45
Littelfuse SE-134C-XGC-00 is a versatile relay with multiple contact configurations, suitable for 50Hz, 60Hz, and ASD frequency operations. It features fail-safe/non-fail-safe relay operation, conforms to standard coating requirements, and offers Front-panel or remote reset options. With harmonic filtering, CT loop monitoring, and a customizable trip time ranging from 0.10 to 2.5 seconds, it is an ideal choice for resistance grounded AC systems.
$9066.28
Littelfuse SE-134C-10 is a versatile relay with multiple configurations and operation modes. It has standard conformal coating and supports 50Hz, 60Hz, and ASD frequencies. With various relay contact options and IEEE device numbers, it ensures fail-safe or non-fail-safe operation. The front-panel switch and remote N.O. contact enable easy reset. Additionally, it provides standard harmonic filtering and resistance grounded AC system support. The relay operates at 24-48V DC supply voltage and offers latching or autoreset function. Its GF trip time ranges from 0.10 to 2.5 seconds and the trip level is adjustable from 0.50 to 12.5 A. The standard features include a front-panel test button and CT loop monitoring.
$7537.37
Littelfuse SE-134C-00 is a conformally coated relay with multiple contact configurations (1 Form A, 1 Form B, 2 Form C). It operates in fail-safe or non-fail-safe mode and supports resistance grounded AC systems. With adjustable trip levels and a test button, it guarantees reliable performance.
$3307.31
Littelfuse SE-107L is a fail-safe relay with 1 Form A (N.O.) contacts, conformal coating for durability, and 50/60Hz frequency compatibility. It provides front-panel or remote N.O. contact reset options. With IEEE device numbers 3GC-50G-50N-51G-51N, it suits resistance grounded AC systems at 120V supply voltage. Its harmonic filtering is standard. Auto/manual reset options are available with latching GC and latching GF. GF trip levels include 0.5, 2.0, and 4.0 Amps.
$2730.20
Littelfuse SE-107E is a frequency-based relay with IEEE Device Numbers 3GC-50G-50N-51G-51N. It has 1 Form A (N.O.) relay contacts with fail-safe operation. It is supplied with 240V AC and features a front-panel switch or remote N.O. contact reset. This conformally coated relay is suitable for resistance grounded AC systems and includes standard harmonic filtering. It also offers autoreset GC or latching GF options and trip levels of 0.5, 2.0, and 4.0 for GF.
$4301.75
Littelfuse SE-107DL is a conformally coated relay module suitable for resistance grounded AC systems operating at 50 or 60Hz. It features 1 Form A (N.O.) relay contacts with fail-safe operation and is compatible with IEEE device numbers 3GC-50G-50N-51G-51N. Reset can be done via front-panel switch or remote N.O. contact. The module provides standard harmonic filtering and supports 120V AC/DC supply voltages. It offers latching GC and GF auto manual reset options, with GF trip levels of 0.5, 2.0, and 4.0.
$3729.06
Littelfuse SE-107D is a conformally coated relay with 1 Form A (N.O.) contacts. Its fail-safe operation ensures reliability. With IEEE device numbers 3GC, 50G, 50N, 51G, and 51N, it offers front-panel switch/remote N.O. contact reset options. Enjoy standard harmonic filtering and compatibility with resistance grounded AC systems. Supports 120V AC and 120V DC supply voltages. Choose from autoreset GC or latching GF options. GF trip levels of 0.5, 2.0, and 4.0 available.
$2730.20
Littelfuse SE-107 is a conformally coated relay with a 1 Form A (N.O.) configuration and fail-safe operation. It has IEEE Device Numbers 3GC, 50G, 50N, 51G, 51N. The reset can be done using a front-panel switch or a remote N.O. contact. With standard harmonic filtering and a system type of Resistance Grounded AC, it operates on a supply voltage of 120V AC. The auto/manual reset options include Autoreset GC and Latching GF. The GF trip time ranges from 0.1 to 2.0 seconds, and the trip level can be set at 0.5, 2.0, or 4.0 amperes.