By Kent · Lock Depot Staff Writer

Four supplies, one enclosure

Von Duprin sells its PS900 family power supplies in four sizes: the PS902 at 2 amps, the PS904 at 4 amps, the PS914 at 4 amps with a 16 amp inrush, and the PS906 at 6 amps. They share the same 14 in. H by 12 in. W by 4 in. D enclosure, and the listings say the boards and accessories swap across them. That makes the choice an amperage decision and nothing else. It is also the decision that most often goes wrong, because a supply that is slightly small does not fail loudly. It gives you a door that works on Monday and drops out on Thursday.

The PS904, PS914 and PS906 listings give UL294 listing, a universal 120 to 240 VAC input and a 12 or 24 VDC output you select in the field. The PS914 and PS906 are also listed Class 2 rated. The PS902 is listed as the 2 amp base supply in the same family, and a PS902 variant is listed at 12 or 24 VDC field selectable.

PS902: 2 amps, one light device

The PS902 is the light duty base supply. The PS904 listing points to it for lighter loads: if the job is one electrified device that does not draw heavily, the PS902 might be enough. I would not stretch it. If the install grows by one more device next year, you have a supply that is already at its limit.

PS904: 4 amps, the mid-range supply

The PS904 is the 4 amp base supply for access control and electronic locking. Its listing says it takes up to two optional distribution boards plus battery backup with two 7A/hr batteries, and that it is the budget choice when the job does not need the PS914's inrush capability. For most mid-range jobs with a few electrified devices that do not spike, it is the right call.

PS914: 4 amps with 16 amps of inrush

The PS914 is the one to spec when electrified exit devices draw heavily on initial activation. The listing's own explanation is the clearest I have seen: the 16 amp inrush rating handles the spike when an EL trim energizes, and a standard 4 amp supply can brown out on that first hit and cause nuisance lockouts. If you are getting intermittent failures on activation, it says, an undersized supply is usually the culprit.

The PS914 listing names the EL trim as the load it was sized for. Our guides to the EL98TP and the QEL on a 9848 show the device side of the same decision.

PS906: 6 amps for the big job

The PS906 is the heavy duty supply: 6 amps of regulated 12 or 24 VDC. The listing says it takes up to three optional distribution boards, or two boards plus battery backup with two 7A/hr batteries. Use it when a door has multiple electrified devices drawing heavy, or when several devices run off one supply. It carries the same enclosure, so everything you have bought for the smaller supplies fits.

Read the part number: base supply or boarded

You will see names like PS904-2RS and PS906-4RL in the catalog. Those are base supplies sold with a board installed: the 2RS is the two relay board and the 4RL is the four relay board with integrated logic. The base supply and the board are the same two things you would otherwise buy separately. If you need a board later, it plugs in. We cover those boards on their own.

PS914RFK: the retrofit kit

The PS914RFK is a different animal. Per its listing, it lets you drop a PS914 power supply into an existing PS873 cabinet without ripping out the old enclosure. If you have a building full of legacy PS873 installations and the customer wants the current PS900 platform, this saves you from patching drywall and running new conduit. It gives the same output as the PS914: 4 amps with 16 amp inrush at 12 or 24 VDC, field selectable, and takes up to two distribution boards plus battery backup. It is packaged to fit the older footprint.

Boards and battery backup

Every one of these is a base supply, and what goes inside it is a separate decision. The PS904 listing says it takes up to two optional distribution boards plus battery backup with two 7A/hr batteries. The PS906 listing says up to three boards, or two boards plus battery backup. The 900 series boards and the 900-BBK backup kit plug into the PS902, PS904, PS906 and PS914, so you can size the supply for the load now and add the board when the job grows.

Which one do I order?

• One light device, no spike: PS902.
• A few devices, nothing heavy on activation: PS904.
• Electric latch retraction or electrified exit devices that draw on activation: PS914.
• Multiple heavy devices on one supply: PS906.
• A legacy PS873 cabinet to upgrade without new conduit: PS914RFK.

The numbers that decide it are the load of each device and its inrush. Add them up before you pick a size, and tell us the device part numbers if you want us to run the sums.

Common questions

What does 16 amp inrush mean on a PS914?

It is the short spike the supply can deliver when an electrified device first energizes, above its 4 amp continuous output.

Do the PS904, PS906 and PS914 use the same enclosure?

Yes. The listings say they share the 14 by 12 by 4 inch enclosure, and the PS906 listing says the boards and accessories swap across the PS902, PS904 and PS906.

Can I switch between 12 and 24 VDC?

Yes. Output is field selectable on the PS904, PS914 and PS906 listings.

Can a PS914 replace an old PS873?

The PS914RFK retrofit kit fits a PS914 into an existing PS873 cabinet.

Does the PS906 hold more boards?

The listing says up to three optional distribution boards, or two boards plus battery backup.

The full range is on our Von Duprin page. Send us the devices on the job and we will size the supply.