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Topic: Excessive current draw by strike lock (Read 3797 times) previous topic - next topic

sonnyyu

FYI

if you need measure current when strike is just on,  ACS712 is disqualify. The di/dt sensor (normally DSP) is needed. i.e. ADE7763 ( cost ~4 at digikey). Oscilloscopes is work around, but not meter.

DaveO

Thanks Papa G

I suppose that the "problem", or non-problem as you may be suggesting, is one of personal perception.

From my point of view, I have a striker rated 350mA for use on AC or DC, which I think should use around 350mA. The fact that my estimation of the size of power supply takes this into account, and I purchase the power supply, and it keeps failing because of the current being far in excess of the 'advertised' rating, becomes a problem for me - it's a matter of perception, you see.

Now that I think I understand the cause of the 'problem'  ( now re-named to 'challenge' to suit various possible perceptions ), I can change things around to suit - will be running the striker from the AC adaptor.

I think that I really have to sincerely Thank everyone that has contributed in any way to this post - I have again learnt so much from this. I really appreciate all the time that you have all taken to reply.

My last question would be :

The wall fitting AC adapter ( 230V to 16VAC 1A ) has 3 terminals. 2 would be the live / neutral. The third is connected directly to the earth pin that plugs into the wall.

Would it be recommended to connect spare wires in the cable to that earth terminal, and then at the gate location where the strike is, connect the same wires to the metal gate frame that the strike lock is inserted into ?


Papa G

Quote
My last question would be :

The wall fitting AC adapter ( 230V to 16VAC 1A ) has 3 terminals. 2 would be the live / neutral. The third is connected directly to the earth pin that plugs into the wall.

Would it be recommended to connect spare wires in the cable to that earth terminal, and then at the gate location where the strike is, connect the same wires to the metal gate frame that the strike lock is inserted into ?


If it's a transformer, the 16VAC secondary should have no relationship, electrically, at all to anything on the primary including earth. The ground terminal is probably there to satisfy the need to blow the fuse/circuit breaker should a primary wire get loose inside the adapter.

Papa G

Quote
From my point of view, I have a striker rated 350mA for use on AC or DC, which I think should use around 350mA. The fact that my estimation of the size of power supply takes this into account, and I purchase the power supply, and it keeps failing because of the current being far in excess of the 'advertised' rating, becomes a problem for me - it's a matter of perception, you see.


Can you post a link to the data sheet for this striker that you are using?

DaveO


Can you post a link to the data sheet for this striker that you are using?


Unfortunately not. This is Africa.

All I can tell you is the specs we have, and 'Made in Spain'

Brand name is not relevant, as I can probably buy the exact same thing with 3 or more different names.


Papa G



Can you post a link to the data sheet for this striker that you are using?


Unfortunately not. This is Africa.

All I can tell you is the specs we have, and 'Made in Spain'

Brand name is not relevant, as I can probably buy the exact same thing with 3 or more different names.




Okay, just curious. I wouldn't place to much weight on the data that you do have, in that case. Trust what you can measure and good luck with your project.

DaveO

Many Thanks Papa G

I really have learnt SO MUCH from this forum.   I am amazed at the number of regular replies by members whose level of knowledge I could only dream of reaching.

My project is moving forward and, strangely, I look forward to the next problem challenge :)

Papa G


Many Thanks Papa G

I really have learnt SO MUCH from this forum.   I am amazed at the number of regular replies by members whose level of knowledge I could only dream of reaching.

My project is moving forward and, strangely, I look forward to the next problem challenge :)



You're welcome, DaveO. Somebody proposed that
Quote
"The beauty happens in the process. Not the final product."
Have fun!

DaveO

Feedback :

I changed the power for the strike lock to a wall wart ( 16VAC ) as discussed, with one wire direct to a striker pin, and the other wire from the wall wart to a relay 'com', and the relay NO to the other striker pin.  The relay is controlled by the Arduino ( well, via a transistor on the relay board, to be more accurate ).

Although the wall wart is only rated 1A  ( the striker was drawing 3.3A on 12VDC ) it is working perfectly.

The only difference is that, on DC there was only a slight 'click' of the coil when it was activated, the AC powered coil makes quite a buzzing noise.  Googling has told me that this is quite normal for an AC powered coil.

I then replaced the wall wart with a 9VAC 1A unit.  ( the striker was rated 8 - 14 V, so I was a little concerned about the 16VAC wall wart output ) and everything still working perfectly.

Thanks to all for the education.

Had the opportunity to put my new knowledge to use again almost immediately.  It struck me that, as the AC makes the striker coil buzz, why was the second gate not buzzing ? ( much heavier duty Cisa Lock ). The Cisa lock is drawing around 2A when activated.

Googled and found that the Cisa lock is designed for 12VAC, and they also make an optional extra bolt-on  'Booster' that can accept 12VDC, 24VDC and 24VAC. It also uses much less current than the 3A it says in the specs for the 12VAC, so I assume that it has some sort of capacitor that stores the charge until it is required. This Booster is said to work well with power from intercom systems, which is around 150mA.

So why is my Cisa lock drawing 2A from my 12VDC supply ?  Quite simple - installed by an 'expert' it didn't have the booster added, and the 12VDC connected directly to the 12VAC coil.

This would explain the lack of "AC on the coil" noise / buzz, and also why the current draw is so high.

To make matters worse, there is no diode over the coil contacts. I am guessing that this would have also added additional strain to my old power supply.

That's the last time any 'expert' is going to install anything like this at my house again !!  If he can't show me that he has a minimum of 200 posts on this forum, and evidence that he actually understand what he is talking about, he can't be trusted.  I am just dumb-struck by the ( non ) expertise of the local installation techies - and that's with the company who has the best reputation in town.

Tomorrow I will disconnect the power to that gate lock until I can source and install the correct booster.

Runaway Pancake

A coil that gets energised by/with AC would have an RC snubber across it, not a diode but performing the same function.
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