Solid state relay SSR-120AA, 120A 70-280V AC to AC

Features

120A 70-280V AC to 24-480V AC solid state relay (SSR) features high structural strength, good impact resistance, and strong shock resistance. The SSR offers a reliable switching the commercial and industrial loads, such as computer peripheral interface device, printing machine, molding machine, food machine, packaging machine, and so on.

• Built in RC absorption
• Photoelectric isolation
• SCR output
• LED indicator for operation status
• Removable protective cover for safety
• Panel mount
• Zero-crossing switch type

Specification

Note:

1. When the load is a resistive load, the maximum load current of the selected SSR should be 2~3 times greater than the actual load current;
   
2. When the load is an inductive load, the maximum load current of the selected SSR should be more than 7~8 times the actual load current.
   
3. When the maximum load current is higher than 10A, a heat sink must be installed to the solid state relay, or the SSR relay should be mounted on a metal base plate with heat dissipation effect, and the thermal grease is applied between them.

Dimension (Unit: mm)

Wiring Diagram

Tips: Overvoltage protection for solid state relays

Transient voltage disturbance is one of the main causes of damage to electronic circuits and equipment. In the process of using solid state relays, instantaneous voltage damage to the solid state relays often occurs.
Common overvoltage protection methods include: RC snubber circuits, metal oxide varistors (MOVs), and built-in transient voltage suppressors (TVS).

1. The RC snubber circuit absorbs and suppresses the momentary voltage applied to the solid state relay and reduces the rise rate of voltage index (dv/dt).
2. MOVs are bipolar protection elements that absorb excessive transient voltages. However, with the energy absorption at each time, the performance of MOVs changes, the voltage level decreases and eventually the risk of overheating occurs due to unbearable supply voltage.
3. TVS (Transient Voltage Suppressors) is efficient silicon PN junction protection device, a new product developed based on the voltage-regulator tube technology. Subjected to a transient high-energy impact at both ends of the TVS tube, it can turn the high impedance at both ends into a low impedance at very high speeds (response time is typically less than a few nS) while absorbing a large current, clamping the voltage between the two poles to a safe value, thus ensuring that the circuit components behind are protected from the impact of transient high energy.