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Solid State Relays

A solid state relay, often referred to as SSR, is an electronic switching device that enables the control of a power output using an input signal without any moving parts. This differentiates it from electromechanical relays, which rely on mechanical contacts to switch loads. Instead, solid state relays employ semiconductor switching elements, such as power transistors, to facilitate the on-off action.

The operation of a solid state relay is initiated by an input voltage, which serves as the control signal. When this control input is applied, the relay allows current to flow from its output to the load. The input and output are typically isolated using optical coupling mechanisms. An opto isolator, for example, can use a light source and a sensor; when the input signal turns the light on, the sensor detects it and allows current to flow in the output circuit.

Solid state relays are notably durable and have longer lifespans than electromechanical relays, primarily because they lack moving parts. This also means they're immune to many environmental factors that might degrade the performance of relays with mechanical contacts. Furthermore, SSRs can handle both AC and DC loads, making them versatile for various applications. When switching AC loads, some solid state relays offer features like zero crossing, which ensures the relay switches when the AC sine wave crosses zero, reducing the potential for electrical noise.

Products

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$148.33
Littelfuse TCR9C is a thermistor sensor with a single setpoint, offering steady state output load rating of 20A and inrush rating of 200A. It features 0.25-inch male quick connect terminals and can tolerate input AC line frequencies of 50/60 Hz with ±15% tolerance. The reset time is less than 150ms, and it has a dielectric breakdown of ≥2000 terminals to mounting surface. With an output voltage drop of approximately 2.0V at rated current, it has an open state leakage current of approximately 5A at 230V. The sensor is electrically insulated for a minimum of 1500Vrms.
$154.70
Littelfuse SIR2B20B4 is a compact and efficient solid-state relay. With an output load rating of 20A, it ensures reliable performance. The 0.25 in. (6.3 mm) male quick connect terminals enable easy installation. Designed for versatility, it has an input tolerance of ±20% and can withstand humidity up to 95% non-condensing. With an insulation resistance of ≥100, this relay guarantees safety. It consumes minimal power, drawing ≤0.5W. Boasting a dielectric breakdown of ≥2000 terminals to mounting surface, it ensures durability. Featuring an output voltage drop of ≅2.0V at rated current, it maintains steady performance. The open state leakage current is ≅6A, and the minimum output load current is ≅50A. The input type is optical isolation LED/photo transistor, offering reliable signal transmission. It operates at an output voltage of 120 Volts.
$154.70
Littelfuse SIR2B20A4 is a 20A output load rating relay with 0.25 in. male quick connect terminals. It has a ±20% input tolerance and operates at 95% non-condensing humidity. It consumes ≤0.5W and has a dielectric breakdown of ≥2000 terminals to mounting surface. The output voltage drop is ≅2.0V at rated current and has an open state leakage current of ≅6A. The minimum output load current is ≅50A. It employs an optical isolation LED/photo transistor for input and operates at 120 Volts.
$154.70
Littelfuse SIR2A20A4 is a 20A output load rating relay with 0.25 in. male quick connect terminals. It has a ±20% input tolerance and is suitable for use in 95% non-condensing humidity. With a power consumption of ≤0.5W, it offers reliable performance. It has a dielectric breakdown of ≥2000 terminals and a minimum output load current of ≅50A. The input type is an optical isolation LED/photo transistor. Its output voltage is 120V, with a voltage drop of ≅2.0V at rated current. The open state leakage current is ≅6A.
$116.22
Littelfuse SIR1B6B4 is a 6A voltage relay with 0.25in. male quick connect terminals for easy installation. It offers optical isolation LED/photo transistor input with a ±20% input tolerance. With a 120V output voltage, it has a ≤0.5W power consumption and insulation resistance of ≥100. The relay is designed with a dielectric breakdown of ≥2000 terminals to mounting surface, making it robust and reliable. Its compact design and non-condensing 95% humidity rating make it suitable for various applications.
$481.82
Littelfuse SCR9L is a versatile solid-state relay with a load rating of 5 A @ 240V or 30V (DC) resistive. It offers an isolated alarm output of 10 A @ 240V or 30V (DC) resistive and is suitable for 1/4 hp @ 125V and 1/2 hp @ 250V applications. The termination type is IP20 screw terminals for up to 14 AWG wire or two 16 AWG wires. It operates at an input AC line frequency of 50/60Hz with a tolerance of ±15%. The encapsulated circuitry provides reliable performance, and the indication system includes green and red LEDs for various statuses. The trip delay type is approximately 10 fixed.
$527.60
Littelfuse SCR630T is an encapsulated SCR with an output load rating of 10 A @ 240 Volts or 30 Volts (DC) resistive. It has screws with captive clamps for up to 14 AWG wire termination. The input AC line frequency is 50/60 Hz with a tolerance of ±10%. It has a trip delay type of ≅6 fixed and is suitable for incandescent load types. The output voltage is ≤250 W @ 240 Volts.
$481.75
Littelfuse SCR490D is an encapsulated SCR with a load rating of 10A @ 240V or 30V (DC) resistive, suitable for incandescent lamps up to 125W @ 120V. It features screw terminations for up to 14 AWG wire and has a trip delay of approximately 6 fixed. Compatible with 50/60Hz AC line frequency.
$481.75
Littelfuse SCR430T is a SCR power controller with a load rating of 10A @ 240V or 30V (DC) resistive. It has screw terminations that support up to 14 AWG wire. The input AC line frequency is 50/60Hz with a tolerance of ±10%. The circuitry is encapsulated, and it has a trip delay of approximately 6 fixed. The output load type is incandescent, and it can handle an output voltage of up to 125W @ 120V.
$216.98
Littelfuse SC4120A is an encapsulated circuitry with a 1A steady state output load rating. It features 0.25 inch male quick connect terminals for easy termination. With an input AC line frequency of 50/60 Hz and a tolerance of ±15%, it is versatile in various applications. The product is highly reliable with a humidity rating of 95% non-condensing and insulation resistance of ≥100. It has a dielectric breakdown of ≥2000 Vrms terminals to mounting surface, ensuring safety. The on/off ratio is fixed at 30 operations per minute.
$193.86
Littelfuse SC3120A is a high-quality, encapsulated circuitry product with a 1A steady state output load rating. It features 0.25in (6.35mm) male quick connect terminals, suitable for easy installation. With an input AC line frequency of 50/60 Hz and a tolerance of ±15%, it ensures reliable performance. The product is designed to withstand humidity levels of up to 95% non-condensing. It offers excellent insulation resistance of ≥100 and dielectric breakdown of ≥2000 Vrms terminals to mounting surface. It operates with a fixed on/off ratio of 30 operations per minute.
$101.10
Littelfuse PHST-38QTN is a probe holder specifically designed for liquid level probes. It is suitable for use in steam pressure environments of up to 240 PSI. With its high durability and functionality, it ensures accurate and reliable monitoring of liquid levels in various applications.