Product Overview
IOR Crydom A4812 Solid State Relay - 480V AC 12A Output, 90-280V AC Control Input
Condition
New old stock, unpacked here for photography. The relay came out of the original orange International Rectifier IOR Crydom box shown with it, which is scuffed and softened at the corners from years on a shelf. Alongside it is a clear poly bag of zinc-plated mounting hardware, folded over at the top rather than heat-sealed. The black epoxy body is clean and the printed panel is fully legible: IOR CRYDOM SOLID-STATE RELAY, A4812, UL and CSA marks, the number 35908 inside a triangle, and ASSEMBLED IN MEXICO. Terminals 1 and 2 are labeled OUTPUT 480V AC 12A; terminals 4 and 3 are labeled INPUT 90-280V AC. The four screw terminals and the aluminum mounting ears show light handling marks only. We have not powered it up.
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Product Overview
The A4812 is a single-phase panel-mount solid state relay from the Crydom A series, the AC-control family: the input side takes line-level AC, 90 to 280V AC across terminals 4 and 3, and switches an AC load of up to 480V AC at 12A across terminals 1 and 2. Those are the figures printed on the relay's own face panel. There are no contacts, no armature, and nothing to arc or pit, which is why these black bricks ended up in heater strings, pumps, and machine panels where a mechanical contactor would have been chattering itself to death. The body is the classic Crydom outline, with a metal base for heatsink or panel mounting and four captive screw terminals under the printed face. The IOR logo stamped beside the Crydom name is International Rectifier, the American power semiconductor company founded in 1947, best known for pioneering the power MOSFET and acquired by Infineon Technologies in 2015 - a useful dating mark, since it places this piece in the years Crydom parts carried the IOR badge. Confirm the derating curve, isolation rating, and heatsinking requirement against the Crydom datasheet for the A4812 before you design it in.
Key Features
- Part number: A4812, printed on the face panel
- Brand: International Rectifier (IOR) Crydom, marked on both the relay and the original box
- Output rating (terminals 1 and 2): 480V AC, 12A
- Control input (terminals 4 and 3): 90 to 280V AC, line-level AC control
- Type: single-phase panel-mount solid state relay, no moving contacts
- Agency marks on the face: UL and CSA, plus 35908 in a triangle
- Marked ASSEMBLED IN MEXICO
- Includes the original box and a clear poly bag of zinc-plated mounting hardware
- Stock: one piece
- Heatsink requirement and thermal derating: not confirmed here - verify against the datasheet before use
Applications
- Maintenance electrician replacing a failed SSR in a 480V heater bank without redesigning the control wiring
- Machine builder switching an AC load from an existing line-voltage control signal, with no DC supply available in the cabinet
- Plastics or packaging technician keeping a legacy band-heater zone alive on original-style parts
- Panel shop stocking a spare for a 480V circuit where a mechanical contactor cycles too often to survive
Frequently Asked Questions
Which terminals are the load and which are the control?
The printed face lays it out. Terminals 1 and 2 are marked OUTPUT 480V AC 12A - that is the switched load side. Terminals 4 and 3 are marked INPUT 90-280V AC - that is the control side, and the wide range is there because this A series relay is driven by line-level AC rather than a low-voltage DC signal.
Does it need a heatsink?
Not confirmed here. Panel-mount solid state relays in this size class are normally bolted to a heatsink or a metal panel with thermal compound, and the allowable current falls off with temperature. Check the Crydom derating curve for the A4812 against your ambient and duty cycle before you rely on the full 12A.
What comes with it?
What the photograph shows: the A4812 relay, the original orange IOR Crydom box it was stored in, and the clear poly bag of zinc-plated mounting hardware that was with it. No heatsink, thermal compound, or terminal covers beyond that.
What am I actually getting, and what am I taking on?
You are getting the relay in the photograph: one A4812, new old stock out of the original International Rectifier IOR Crydom box, with the hardware bag that was stored alongside it. What you are taking on is that we have not powered it up - no control voltage, no load, no leakage or switching test has been run here, so it is sold on its markings and its appearance. Those markings are legible before you commit: the A4812 number, OUTPUT 480V AC 12A, INPUT 90-280V AC, the UL and CSA marks, and the condition of all four screw terminals. The photograph is the spec for this piece. If your job needs a documented test report, buy new; if you need a known, marked, correctly rated SSR for one socket in a panel, this is a straightforward way to get it. Shipping is a flat $8, free once your order passes $28, and orders leave our Idaho warehouse the same or next business day.
International Rectifier built its name on power silicon that never moves, and this brick is that idea bolted to a panel - no armature, no click, nothing to wear out but time. Hand it a control line and let it go back to the quietest job in the cabinet.
