Archive for August, 2012|Monthly archive page

Fail Safe/Secure with PP8FR

Saturday, August 25th, 2012

I have been asked how to power the locks for a fail safe/fail secure door using the PP8FR.

Fail safe/secure doors use two electric locks, one to release on fire or emergency and one to stay locked to maintain access control back into the building.

Often this is achieved by controlling the negative/ ground connection via the access control relay. The ground connection is fed from the power supply to the relay common and then the N/C and N/O relay contacts are fed, one to each lock so that when a card is presented the fail safe lock looses power and the fail secure lock turns on allowing access.

The problem comes when you need to fire trip the fail safe lock. The fail secure lock can’t be fire tripped as it will stop working. This is solved by breaking only the positive power feed to the fail safe lock. This can be easily done using separate fused outputs from the PP8FR. See diagram below.

Fail Safe/Secure with PP8FR

Fail Safe/Secure Door Set Up

The actual relay contacts used will vary depending on how the manufacturer labels their outputs. This method also has an added advantage, if one of the locks is tampered with and/or goes short circuit then only one fuse will blow leaving the other lock still functioning and keeping the door secure.

Coming Soon: ATMOD Pre-built End Of Line Resitor Module

Saturday, August 18th, 2012

Sneak peak at new ATMOD from Jack Fuse. Due for official release in September 2012.

The ATMOD makes installing End of Line resistors for security & access control systems easier than ever before. It features an on board resistor network and special push in connectors that allow technicians to make mistake free terminations in seconds.

Just strip your alarm cables and insert the wires directly into the ATMOD, no teminal driver, crimping or soldering and no more broken resistors. Best of all you will never suffer from another incorrect or back to front resitor network.

ATMOD EOL resitor alarm network

Red = 10K/10K DEOL resistors

ATMOD EOL reed switch

ATMOD terminated to a reed switch

Watch this space for more information and a release date. The ATMOD will be available from leading alarm wholesalers in a range of common DEOL resistor values.

Care when terminating.

Saturday, August 11th, 2012

Recently one of my re-sellers had to rush to site with a replacement module for a PP8FR that had a “faulty” output. Fuse one would blow every time power was applied to the board.

On inspection I removed the main output terminal plug and found a single strand off copper shorting the output. I brushed it off and the unit worked like new.

It is sometimes easier to terminate to the main output plug while removed from the PP8FR. In this case while striping/cutting the cables the tech had inadvertently dropped strands of copper onto the board and one got stuck behind the replaced plug. A simple enough mistake to make and a good reminder to take care when terminating around exposed electronics. If the copper had fallen on a controller the cost could have been considerable.

Wasp Cam

Thursday, August 9th, 2012

Clearly well maintained!