Electromechanical locks

[SidM]

I've searched through the forum on how the subject locks work but don't seem to understand the explanations given.  Would someone clarify in simple terminology how these locks work, how they differ from electromagnetic locks and, more importantly, are the fire safety implications any different for electromechanical locks than they are for electromagnetic locks.  

If there are any pictures (I can't seem to find any) that show these locking devices in action, it would help me get a better understanding of the pros and cons.

[David Rooney]

In very simple terms an electromagnetic lock would commonly be a "maglock". An armature with metal plate that becomes magnetised when power is applied. Attach this to a solid piece of wall and screw a metal plate to the door and hey presto the door is held closed until such time the power is removed from the armature.

No moving parts therefore could last forever.

This is the basic "failsafe" method for releasing doors when power fails. Although there are certain instances where you may wish to battery back the system to keep the doors locked in certain secure installations etc.

An electromechanical lock would generally have a moving mechanism, eg. there would be a draw bolt that physically moves in order to secure the door. Or more commonly if you imagine a yale lock, the keep located in the door frame would have a hinged strike plate that is fixed in position under normal conditions (power applied) but would become free when power is removed, allowing the latch bolt to move the strike plate and push passed it without the bolt physically being drawn back by hand. ie turning a handle.

This is also failsafe and can be installed the other way round.

There can be issues with both methods, commonly residual magnetism in the maglock not releasing the plate, hence double pole isolation of the power directly to the magnetic, and mechanical failure of the second type or poor fitting that would mean the door couldn't be opened in an emergency.

[kurnal]

The most common pitfall of the electromechanical lock is that it often will not release if under pressure- for example if you are pushing against the door and then hit the release button the strike plate will not release until the pressure is released from the door. So in a panic situation with persons pushing to get out this could be a problem.

[Izan FSO]

The most common pitfall of the electromechanical lock is that it often will not release if under pressure- for example if you are pushing against the door and then hit the release button the strike plate will not release until the pressure is released from the door. So in a panic situation with persons pushing to get out this could be a problem.

Would both of the above type locking devices need to be linked to the fire alarm and release on activation? therfeore unlikely that a panic situation could ensue because the fire alarm will be sounding and therfore relased before any amount of persons are at the door escaping.....just a thought!!

[kurnal]

Depends. Ideally yes we would link to the fire alarm and povide a green break glass box as a backup. But many occasions arise where security considerations over ride this. And even if there is a link we assume that the fire alarm will be sounding before anyone tries to use the exit- which may not be always be the case.

[SidM]

In very simple terms an electromagnetic lock would commonly be a "maglock". An armature with metal plate that becomes magnetised when power is applied. Attach this to a solid piece of wall and screw a metal plate to the door and hey presto the door is held closed until such time the power is removed from the armature.

No moving parts therefore could last forever.

This is the basic "failsafe" method for releasing doors when power fails. Although there are certain instances where you may wish to battery back the system to keep the doors locked in certain secure installations etc.

An electromechanical lock would generally have a moving mechanism, eg. there would be a draw bolt that physically moves in order to secure the door. Or more commonly if you imagine a yale lock, the keep located in the door frame would have a hinged strike plate that is fixed in position under normal conditions (power applied) but would become free when power is removed, allowing the latch bolt to move the strike plate and push passed it without the bolt physically being drawn back by hand. ie turning a handle.

This is also failsafe and can be installed the other way round.

There can be issues with both methods, commonly residual magnetism in the maglock not releasing the plate, hence double pole isolation of the power directly to the magnetic, and mechanical failure of the second type or poor fitting that would mean the door couldn't be opened in an emergency.

Sorry, I can't picture that (electromechanical lock) in my head and nor do I understand any of the definitions of an armature on the web as they all appear to be in electricians' speak.

[Midland Retty]

Hi SidM

The device David refers to is essentially a big magnet. Below is a very crude description of how it works:-

Picture a metal "block" (for want of a better description) fitted to the top of a fire door.

On the corresponding frame there is another metal block

When the door is in the closed position the metal blocks touch one another.

When an electrical current is provided to one of the metal blocks it becomes magnetised and is attracted to the other metal block - it becomes a magnet - and the magnetic force between the two blocks hold the door closed.

You cant open the door until the power is cut to the metal block and it becomes de-magnetised.

There are other different types of elctromechanical locks. All generally use a power supply to actuate a lock and hold a door in the "locked" or "shut" position, and its only until you cut or interupt the power supply that the lock releases.

No doubt Wiz (if he were here) would be able to explain this better but hopefully the above helps.

[SidM]

Thanks much appreciated.

[kurnal]

Theres not a bad description of an electromagnetic lock or electric keep in the RRO fire safety guides- the section covering guidance on means of escape

[AnthonyB]

Electromechanical lock (electronic keep)

Take one door with a standard rim latch:



Replace the fixed locking plate in the above picture with your Electronic keep:





attach to your door entry system & you can buzz people in as the device releases the locking plate so the door pushes open with the latch still in the 'locked' position. To exit you unlock the latch with the turn knob or hansle as normal.

The Electro MAGNETIC lock is as described in post  #7 & pictured below;

[SidM]

Electromechanical lock (electronic keep)

Take one door with a standard rim latch:

http://i255.photobucket.com/albums/hh130/contactacb/rimlatch.jpg

Replace the fixed locking plate in the above picture with your Electronic keep:

http://i255.photobucket.com/albums/hh130/contactacb/Electronickeep2.gif

http://i255.photobucket.com/albums/hh130/contactacb/Electronickeep1.jpg

attach to your door entry system & you can buzz people in as the device releases the locking plate so the door pushes open with the latch still in the 'locked' position. To exit you unlock the latch with the turn knob or hansle as normal.

The Electro MAGNETIC lock is as described in post  #7 & pictured below;

http://i255.photobucket.com/albums/hh130/contactacb/maglock.gif

Links don't work?

[CivvyFSO]

SidM, try this:

Click 'profile' then click 'display' then check the 'show images in posts' box.

[SidM]

SidM, try this:

Click 'profile' then click 'display' then check the 'show images in posts' box.

Where do you click profile?  At the moment, all I get is a blank web page.

[devon4ever]

Am I correct in assuming that this is a similar application of the magnet thingy - entry door to a block of flats for instance, whereby you can gain entry by an electronic key fob or by using the intercom to alert a resident to get them to open the entrance door? if so then my question is: does the entrance door become accessible during a fire alarm activation and does this compromise security of the building?

[Midland Retty]

Hi Devon

Yes its generally the same principle more or less.

In terms of the security issue most entrance doors I have come across that do have swipe cards / fobs facilities dont open on the fire alarm.

Instead there will be a thumb turn on the inside leaf or emergency release switch.

In public places this may be different however, but then again you probably won't have that type of access control in place at premises ferquented by members of the public.