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Solid State Relay

Overview Solid State Relay

The solid-state relay (SSR) is an electronic switching device that switches on or off when an external voltage is applied across its terminals. Solid State Relays (SSRs) generally switch high voltage circuits on and off using the low voltage at their control terminals. A solid-state relay (SSR) does not include moving parts, making it less prone to wear and tear and more reliable than a mechanical relay. SSRs are typically used where control signals are produced by digital circuitry, such as microprocessors or programmable logic controllers (PLCs), and AC or DC loads are controlled. Besides industrial controls, lighting controls, HVAC, process controls, and other applications requiring high voltage or high current loads, they are also used to switch loads of high voltage and high current. Solid-state semiconductors utilize semiconductors’ electrical and optical properties instead of moving components to control input-to-output actions.

It is an electronic switching device made of semiconductors with no movable parts. Due to no moving components, it is a Solid State Relay, and thus does not undergo any wear and tear on contact, making it long lasting for up  to 100 million operations.

What does Solid State Relay do?

  • The major function is to switch “ON” or “OFF”  and control a high voltage load.
  • It provides complete electrical isolation between their input and output contacts.
  • Solid State relays control the power using a relatively low voltage input.

How does a Solid State Relay work?

  • Solid State Relay input circuit: The input circuit is responsible for relaying the signal to the control system. Once the input voltage changes, the circuit activates if the input voltage exceeds the relay’s voltage range and deactivates if input voltage drops below the range.
  • Solid State Relay Coupling: It is a relaying interface between the input circuit and output circuit of the SSR. It isolates the two circuits operating at different reference voltages and prevents high output load from flowing to input. SSR Coupling transmits the energization and de-energization commands to the output circuit.
  • Solid State Relay trigger circuit: It drives the relay action to the system load and triggers the current to flow in the load circuit turning it ON. It may depend on the type of output load such as zero-switching, DC Switching, peak switching etc.
  • Solid State Relay Output Circuit: It connects the SSR to the load that is supposed to be controlled. Once the trigger switches On, current flows in the output circuit and resultantly switching ON the load.

Advantages of SSR

  • Since it has no moving part, it has a longer lifespan than the electromagnetic relays.
  • There is no physical contact, thus no contact sparks and wear out.
  • It has high speed and hush frequency function due to use of optical and electrical signals for transmission.
  • It generates no electrical arch or noise because it shuts down at 0 AC load, avoiding fire hazards.
  • It requires much less power to operate as compared to standard mechanical relays.
  • It is stable even in case of any movements.
  • They are great for using in difficult conditions like shock, vibrations and dust.
  • They are compact in size.

BCH Solid State Relays:

  • BCH Solid State Relays are widely ranged from 12A to 125A expanding their applications 
  • BCH SSR has a narrow relay range with current monitoring and temperature controller PID.
  • They have a high switching frequency and a long life expectancy.
  • BCH Solid State Relays are compact in size with an input voltage range of 3 to 32 VDC.
  • BCH can provide SSRs with input voltages other than those already available on demand.

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 where frequent and high-frequency switching is needed. Due to its unique advantages, it is used to control AC or DC circuits by allowing smaller inputs to control larger output signals. thus, making them useful in many domestic electronics and industrial motor control applications, as stated below:

  • It is used in motor control in both AC and DC motors to alter the speed, as in regulating fans, power switching, etc.
  • SSRs can be programmed to switch the load in the event of a high AC power supply and protect the motor from damage caused by high inrush current.
  • SSR are used in lighting controls for switching loads such as light bulbs and LEDs. In these cases, Solid State Relays provide fast switching speeds. Furthermore, because there is no contact bounce, light flickering is avoided.
  • They are used in heating and cooling systems such as electric heaters, air conditioners, electric ovens, industrial heaters, and furnaces  to control the temperature.
  • Medical Devices finds a fitting use of controllers with Solid State Relays, since they are faster, highly reliable, and use very low input.
  • SSR is used in communication lines and Optocouplers due to its reliable and fast switching system.
  • Automotive systems use SSR in engine management systems, headlight dimming circuits, and fog light control applications. It facilitates a more precise load switching system and automation in controls.
  • Solid State Relays are mostly used in high load switching in transformer control.
  • Water Pumps also find use for SSR in electric motors used for switching the pump on or off.

BCH Solid State Relays are the most suitable switching systems available today with their longer life, sensitive and faster functions. They are used as an effective and reliable switching mechanism in the majority of electrical systems in both domestic and industrial settings.

BCH Solid State Relay are ideal for an application that requires high switching frequency and can be used in harsh environments like shock, vibration, and dusty environments.

Solid State Relay electronically switches power to a load circuit, and Solid State Relay has no moving parts. Therefore, there is no mechanical wear and tear on contacts. The life expectancy of Solid State Relay is over 100 million operations.
BCH Solid State Relay is widely used in heating control, Motor control, capacitor switching and lighting control, solenoid, transformer control, and air conditioning applications.

The BCH electronic switching device is used for external voltage (AC or DC) for controlling terminals. While serving the same functions as an electromechanical relay, expect moving parts. Solid State Relay differs from a general relay, does not contain any mechanical contacts, and mostly uses electronic parts. Thus, Solid State Relays have wide features.

BCH Solid State Relay ranges from 12A to 125A. In which single-phase and three-phase Solid State Relay 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 that has input voltage 3 to 32VDC while other voltages are on request.

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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