By Kent · Lock Depot Staff Writer

The 900 series are boards, not supplies

When someone asks for a Von Duprin "900 series" part, they mean the plug-in boards that go inside a PS900 family power supply. They are not power supplies themselves. A 900-2RS, 900-4R, 900-4RL, 900-8F or 900-8P sits in a PS902, PS904, PS914 or PS906 enclosure and decides what happens to the power once it leaves the supply. The listings call them plug and play: no wiring harness, no adapter.

Pick the board by how many devices it has to run and what happens when one of them has a fault.

900-2RS: two relays, two electrified devices

The 900-2RS is a two relay board for electrified panic hardware. Each relay controls one electric latch device independently, so when door 1 gets a request to exit, door 2 stays locked. The listing's example is the two door vestibule with two EL exit devices, and calls it the board for that. The version with fire alarm integration is the 900-2RS-FA, which carries the fire alarm relay pre-installed and saves a separate 900-FA module and a board slot.

900-4R: four relays, no logic

The 900-4R is four independently controlled relays, which gives each of three or four electrified devices its own circuit, so a fault or an activation on one does not affect the others. The listing names lobby configurations, multi-door entries and retail storefronts where you want centralized power distribution. The FA version is the 900-4R-FA.

900-4RL: the interlock board

The 900-4RL is four relays with integrated logic. The listing says it is what gets specified on mantrap, airlock and sally port configurations: door A cannot unlock until door B is secured, and the reverse. Without it, you need a separate interlock controller above the door and the wiring to connect it, and this board puts the logic in the supply enclosure. The listing calls the sequencing programmable. The FA version is the 900-4RL-FA.

900-8F and 900-8P: eight outputs, two kinds of protection

Both give you eight individually protected outputs. The difference is what protection means.

• 900-8F: an individual glass fuse per output. If one device shorts, it blows its own fuse and the other seven keep running. The cost is a service call to replace the fuse.
• 900-8P: PTC auto-resetting outputs. When an output draws too much current, the element cuts power to that output, and it resets once the fault clears. No trip back to the site for a fuse.

The listing for the 900-8P says the board pays for itself the first time it saves a service trip. On a large installation that is a fair claim. On a small one with two devices, you are not buying the 8 output board in the first place.

FA: the fire alarm relay versions

Each of the boards above has an -FA version listed, with the fire alarm relay built in. The listings say it saves you from adding a separate 900-FA module and burning a board slot. If the job needs that input on the board, order the FA version up front. Swapping later means pulling a board you already paid for.

Battery backup: BBK, BB and BAT

Three part numbers, three different jobs.

• 900-BBK: the complete kit, a board plus two 7A/hr batteries. The listing says it keeps electrified exit devices operational for up to 4 hours, depending on load.
• 900-BB: the board only, for when you already have batteries.
• 900-BAT: the two 7A/hr replacement batteries. You need the 900-BB board installed to use them.

Batteries do not last forever. The listing says that if your backup test fails or the battery LED on the supply shows a fault, the 900-BAT is the replacement. They are compatible with the PS902, PS904, PS906 and PS914.

Which supplies take the boards

The listings name the same four compatible supplies for the relay boards: the PS902 at 2 amps, the PS904 at 4 amps, the PS914 at 4 amps with 16 amps of inrush, and the PS906 at 6 amps. The battery backup listings name the same four. If you already own one of these supplies, any of the boards drops in without an adapter.

The mistake I see is buying a board for a supply that cannot carry the load. A four relay board does not add amperage. It spreads what the supply has. If three electric latch devices all energize at once on a 2 amp supply, the board is not the problem, and you will chase it for a week before someone checks the supply.

Which supply holds how many boards

The supply sets the limit. The PS904 listing says up to two optional distribution boards plus battery backup. The PS906 listing says up to three optional distribution boards, or two boards plus battery backup. Add up the boards before you pick the supply, and our guide to the EL98TP shows why the supply side matters.

Which one do I order?

• Two EL devices on a vestibule: 900-2RS.
• Three or four devices on one supply: 900-4R.
• A mantrap, airlock or sally port: 900-4RL.
• Eight devices, you want fuses: 900-8F. You want no service calls: 900-8P.
• Backup power: 900-BBK new, 900-BAT to replace the batteries.

Common questions

Are the 900 series parts power supplies?

No. They are plug in boards for the PS900 family supplies.

What is the difference between the 900-4R and the 900-4RL?

The 4RL adds integrated logic for security interlocking and sequencing.

900-8F or 900-8P?

The 8F uses fuses and needs replacing after a fault. The 8P uses PTC outputs that reset themselves.

How long does the 900-BBK run the doors?

The listing says up to 4 hours, depending on load.

What does the -FA suffix mean?

The board carries the fire alarm relay pre-installed.

The full range is on our Von Duprin page. Tell us how many devices, which supply and whether doors interlock, and we will name the board.