Omron G3NB-225B-1 — Solid State Relay, 25 A, DC5-24 V
SKU: G3NB-225B-1USD 8.00
G3NB solid state relay, 25 A load at AC24-220 V, DC5-24 V input, zero-cross switching, built-in varistor.
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Product Overview
The Omron G3NB-225B-1 is a solid state relay in the G3NB family, rated for 25 A continuous load current at AC24-220 V when mounted on a Y92B-N150 heat sink at 40 °C ambient. The DC5-24 V control input drops onto any PLC transistor output or sensor signal, and the relay switches the load at the AC zero-cross point to reduce inrush noise. The 'B' suffix marks zero-cross switching; the '-1' suffix marks the DC5-24 V input range. It is the standard pick for heater bands on extruders and injection moulders, heat-seal jaws on packaging machines, and any other resistive load that needs silent, fast, and bounce-free switching.
Why zero-cross vs non-zero-cross
A zero-cross SSR turns the load on at the next AC zero-voltage point after the control input is asserted, which removes the high di/dt inrush that would otherwise hit a cold heater or transformer. For purely resistive loads (heaters, lamps), zero-cross is always the right pick. For inductive or phase-angle control, the G3NB-D210B (random turn-on) is the alternative. For higher DC loads, the G3RD series covers DC switching.
Heat sink sizing
The 25 A rating only holds with the Y92B-N150 heat sink bolted to the relay; surface mounting drops the rating by 30 %. Below 25 A the relay runs cooler and can use a smaller Y92B-N100 (for 20 A) or Y92B-N50 (for 5-10 A) heat sink. For DIN-rail mounting, the R99-12 one-touch mounting plate fits the G3NB line. Always allow space above and below the relay for convection.
Before ordering
Confirm the load current is at or below 25 A at the actual ambient temperature, with the right heat sink fitted. Confirm the control signal is DC5-24 V (the '-1' suffix). For DC input around 100/200 V, the G3NB-225B-2 covers that range. Add a fast-blow fuse on the load side for short-circuit protection of the SSR output.
Key Features
- G3NB solid state relay, 25 A continuous load at 40 °C
- AC24-220 V load, zero-cross switching
- DC5-24 V control input (low-side trigger)
- Built-in varistor absorbs external surge
- LED operation indicator on the input side
- Photocoupler isolation, 2500 V AC dielectric
- UL / CSA / TUV certified, protective cover for safety
- SKU: G3NB-225B-1
- Series: G3NB solid state relay
- Voltage: 220 V
- I/O: 5 I/O
Best-Fit Applications
- Heater band switching on plastic extruders and injection moulders
- Heat-seal jaw temperature control on packaging machinery lines
- Resistive furnace or oven element control on a process line
- Solder pot or reflow oven element switching in electronic assembly
- Lamp or infrared heater control on a drying tunnel
Buying Checklist
- Choose G3NB-225B-1 for 25 A zero-cross at DC5-24 V input.
- Choose G3NB-220B-1 for the same family at 20 A (smaller heat sink).
- Choose G3NB-240B-1 when the load needs 40 A continuous.
- Choose G3NB-D210B for random turn-on switching of inductive loads.
- Choose G3PE-225B for a single-package SSR with built-in heat sink.
- Confirm the load is at or below 25 A with the right heat sink fitted.
Technical Specifications
| Series | G3NB solid state relay |
|---|---|
| Load Voltage | AC24-220 V (47-63 Hz) |
| Load Current | 25 A continuous at 40 °C with Y92B-N150 heat sink |
| Control Input | DC5-24 V (operate 4-32 V, release 1 V max.) |
| Input Current | 7 mA max. at 24 VDC |
| Switching Mode | Zero-cross (B suffix) |
| Surge Protection | Built-in varistor |
| Output Device | Triac |
| Isolation | Photocoupler, 2500 V AC dielectric |
| Operation Indicator | LED (lit when input is on) |
| Heat Sink | Y92B-N150 (required for 25 A rating) |
| Certifications | UL, CSA, TUV |
Resources & Downloads
FAQ for G3NB-225B-1
What heat sink do I need for the G3NB-225B-1?
For the full 25 A rating at 40 °C ambient, fit the Y92B-N150 heat sink. The smaller Y92B-N100 covers up to 20 A, and the Y92B-N50 covers up to 10 A. Surface-mounting without a heat sink drops the rating by 30 %. Add the R99-12 one-touch mounting plate for DIN-rail installation of the SSR and heat sink.
Can the G3NB-225B-1 switch a transformer or motor?
It can, but zero-cross switching is the wrong pick for inductive loads. For transformers, solenoids, or small motors, choose the G3NB-D210B random turn-on SSR or use a contactor instead. For purely resistive loads like heaters or lamps, the zero-cross G3NB-225B-1 is the correct pick.
What fuse should I use on the load side?
Fit a fast-blow semiconductor fuse rated at about 1.5 x the load current. A 25 A SSR typically pairs with a 40 A fast-blow fuse. The fuse protects the SSR triac from a load-side short circuit, which the SSR itself cannot clear.
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