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Solid State Relay

Introduction of Solid State Relay

The Solid State Relay (SSR) is an electronic switching device that is activated by applying an external voltage across its terminals. By applying a low voltage to the control terminals of Solid State Relays (SSRs), they can generally switch high-voltage circuits on and off.

The Solid State Relay (SSR) does not have moving parts, making it more reliable than a mechanical relay. When a programmable logic controller (PLC) or microprocessor produces control signals, Solid State Relay are typically used to control AC or DC loads. In addition to industrial controls, lighting controls, HVAC, process controls, and other applications requiring high voltages or currents, they are also used for switching high voltages and currents. Rather than using moving components to control input-to-output actions, solid-state semiconductors use their electrical and optical properties.

This electronic switching device consists of no moving parts and is made of semiconductors. It is a Solid State Relay since there are no moving parts. It does not undergo wear and tear on contact, making it long-lasting for up to 100 million operations.

Solid State Relays (SSRs) Types

Solid State Relays can be classified into the following types based on their applications and switching methods:

  • Instant ON Solid State Relay
  • Zero Switching Solid State Relay
  • Peak Switching Solid State Relay
  • Analog Switching Solid State Relay

Instant ON Solid State Relay

Solid State Relay with instant ON function switch on the load circuit as soon as there is sufficient input voltage. Input voltage is removed when the load current crosses the next zero, and the device turns off. Inductive loads can be controlled by instant ON SSRs. Magnetic valves, contactors, starters, and switching contactors are some of the practical applications.

Zero Switching Solid State Relay

Zero-switching Solid State Relay are designed to turn on whenever the load ac voltage crosses the next zero voltage. The load AC voltage reaches zero volts when the input voltage is removed. In order to operate a zero-switching relay, a zero-crossing circuit is used. In the zero-crossing circuit, the TRIAC is activated when there is a zero-crossing in voltage. Zero-switching relays are mainly intended for controlling resistive loads. Applications include temperature control of heating elements, soldering irons, and ovens.

Peak Switching Solid State Relay

Peak switching Solid State Relay are enabled when the output ac voltage reaches its next peak after applying the control input voltage. When the input control voltage is removed, and the output AC current crosses zero, it turns off. In a peak control circuit, the output AC voltage is detected when it reaches its peak, and the TRIAC is fired when it does. A transformer, a large motor, or a heavy inductive load can be controlled with these switches.

Analog Switching Solid State Relay

Depending on the input voltage amplitude, analog switching Solid State Relay switch. Analog switching Solid State Relay have a proportional starting output voltage to their input control voltage. A switch is triggered when the control input voltage is removed and the output ac current crosses zero. The analog switching SSRs are equipped with synchronizing circuits that control the output voltage according to the control input voltage.

It is primarily designed for closed-loop applications like temperature control in that analog switching Solid State Relay are used.

What does Solid State Relay do?

  • This device primarily controls high voltage loads by switching them “ON” or “OFF.”
  • This device provides electrical isolation between its input and output contacts.
  • With Solid State Relays, relatively low voltages are used to control the power.

What is the process of operating a Solid State Relay?

  • Solid State Relay input circuit: Signals are relayed from the input circuit to the control system. In case of an input voltage exceeding the relay’s voltage range, the circuit is activated, whereas, in case of an input voltage below the range, the circuit is deactivated.
  • Solid State Relay Coupling: A relay coupling connects the input circuit to the output circuit of a solid state relay. By isolating the two circuits and preventing high output loads from flowing to the input, it isolates the two circuits that operate at different reference voltages. In the output circuit, the Solid State Relay Coupling transmits energization and de-energization commands.
  • Solid State Relay trigger circuit: It triggers the flow of current in the load circuit, triggering the relay action to turn on the load. It depends on the output load type, such as zero-switching, DC switching, or peak switching.
  • Solid State Relay Output Circuit: The Solid State Relay is connected to the load it is supposed to control. Upon switching on the trigger, current flows through the output circuit, and the load is switched on.

Advantages of Solid State Relay

  • It has a longer lifespan than electromagnetic relays because it has no moving parts.
  • Due to the lack of physical contact, no sparks or wear are generated.
  • Due to its optical and electrical signal transmission capabilities, it has high-speed and low-frequency capabilities.
  • A fire hazard is avoided by shutting down at 0 AC load, which generates no electrical arch or noise.
  • Relays using standard mechanical components need much more power to operate.
  • In spite of any movement, it remains stable.
  • They can handle shock, vibrations, and dust without any problems.
  • The size of these devices is compact.

BCH Solid State Relays:

  • BCH Solid State Relays wide range from 12A to 125A, expanding their applications 
  • BCH Solid State Relay has a narrow relay range with current monitoring and temperature controller PID.
  • Their switching frequency is high, and their lifespan is long.
  • Among the features of BCH Solid State Relays are their compact size and their ability to accept voltages ranging from 3 to 32 volts DC.
  • In addition to those already available on demand, BCH can deliver Solid State Relay with various input voltages.

Applications of Solid State Relays

Solid State Relays are more convenient and durable devices as compared to convection switching devices, making them handy in applications. They are most commonly used in applications requiring frequent and high-frequency switching. Due to its unique advantages, it can control AC or DC circuits with smaller inputs and larger output signals. As a result, they are useful for industrial motor control and domestic electronics, such as:

  • It is used to control the speed of both AC and DC motors and fans, power switches, and so forth.
  • Motors can be protected from damage caused by a high inrush current by using Solid State Relay that switch the load when an AC power supply exceeds a certain threshold.
  • The speed of AC and DC motors can be controlled, as well as the speed of fans and power switches.
  • Using Solid State Relay for lighting controls, such as switching light bulbs and LEDs, is common. Solid State Relays can be used in these cases since they enable fast switching speeds. Additionally, no contact bounce prevents light flickering.
  • For controlling the temperature, they are used in heaters, air conditioners, electric ovens, industrial heaters, and furnaces.
  • Controllers with Solid State Relays are ideal for medical devices since they are fast, highly reliable, and require very little input.
  • The reliability and speed of Solid State Relay make them ideal for use in communication lines and optocouplers.
  • The use of Solid State Relay is widespread in automotive applications, such as engine management systems, headlight dimming circuits, and fog light control circuits. By automating controls, you can switch loads more precisely.
  • The use of Solid State Relay is widespread in automotive applications, such as engine management systems, headlight dimming circuits, and fog light control circuits. By automating controls, you can switch loads more precisely.
  • Solid State Relays are mostly used in high-load switching in transformer control.
  • Water pumps also find Solid State Relay use in electric motors for switching the pump on or off.

BCH Solid State Relays are the most suitable switching systems available today with their longer life, sensitivity, and faster functions. Domestic and industrial electrical systems use them as effective and reliable switching mechanisms.

A BCH Solid State Relay is ideal for applications requiring high switching frequencies and can withstand harsh environments such as shock, vibration, and dust.

Solid State Relays have no moving parts and switch power to a load circuit electronically. As a result, there is no mechanical wear and tear on contacts. Over 100 million operations are expected to be performed by Solid State Relays during their lifetimes.

In addition to heating and motor control applications, BCH Solid State Relays are also used for capacitor switching and lighting control, solenoids, transformers, and air conditioning.

While serving the same purpose as an electromechanical relay, expect moving parts. A solid state relay differs from a general relay in that it primarily comprises electronic components and does not contain mechanical contacts. Thus, Solid State Relays have wide features.

BCH Solid State Relays range from 12A to 125A. Which single-phase and three-phase Solid State Relays are available with low-level output control without interfacing. Its narrow Solid State Relay range has current monitoring & temperature controller PID with high switching frequency and longer life. Solid relay has a compact size with an input voltage of 3 to 32VDC, while other voltages are requested.

Specification and Features Solid State Relay

  • Range 12A to 125A
  • Single phase and three phase Solid State Relay
  • Slim Solid State Relay range (22.5mm) with current monitoring & temperature controller PID
  • Input Voltage 3 to 32VDC ,Other voltages on request
  • High switching frequency and longer life
  • Reliable and quite operation
  • Compact size
  • Low level output control possible without interfacing
  • CE Certification Marked


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