Timer Problem Green Brook T80-C

[monjoor]

Hi peeps, I have been using these 24 hour 7 day din rail timers over the last year or so.

It has a override switch which permanently switches on the relay. The problem I am having is that the relay drops out after 1 minute after the override switch is pressed.

The same problem occurs when the timer switches on based on the time it is set but drops out after a minute from the time it switches on.

I suspect it is a batch fault but Green Brook won't say anything direct.

Anybody else having the same problem?

 

[Darkwood]

http://greenbrook.co.uk/pdf/T80-C.pdf

Reset the unit and follow the instructions, ensure you have adhered to the warnings about programming the times and that you need to do both hours and minutes even if the time set is 6am you need to set hrs 06 and minutes 00 ...

I haven't used this timer but scanned through the programming and install link and saw a few area's you may have made an error in programming.

Ensure you have followed them to the T and then and only then would i consider a faulty unit but 2 faulty units hmm.. you need to double check your set-ups.

 

[tazz]

Can`t ad much to above, but check to see if the fault occurs without any load connected.

 

[monjoor]

Looks like I've found the problem. For some odd reason it seems to be the din rail power supply that is causing the time switch to drop out.

I am lighting up some LEDs at 800mA 12vdc and the din rail power supply is rated at 1.25A

Tried with another brand of power supply it worked fine no drop out.

It's a bit bizarre to me as I see the timer switch as a volt free contact rated at 16A or 2A Inductive. It's just a relay switching it's contact, even if I did put 20amps through it it's only matter off burning the contacts unless the timer has got some safety feature that drops the relay if load condition is exceeded.

 

[Darkwood]

It may be the control voltage dropping to the timer (If it powered off the same power supply). .it will have edge triggering to pull relay in and out but if it gets enough VD on its supply terminals the relay will drop out and will not re-engage until next on cycle, this will be nothing to do with loading on the volts free contacts.

Thanks for the feedback!

 

[monjoor]

Thanks for the feedback,

"Control voltage dropping" almost for example like a brown out where contacts drop out but in this case enough dip in voltage for the relay to drop out?

 

[Darkwood]

Does the timer use mains diect to power it or is it powered by an isolating transformer whether same voltage or reduced.... if this is undersized for the various loads it may have attached then you will get voltage issues which may create the issue ive mentioned above ... as I dont know the setup i can only guess a possible cause..... as the timed supply holds for approx 1min it could be a fault on a fitting where say a ballast starts to break down when it gets hot only .... this could draw a large current which is enough to drop the voltage but doesnt last long enough to trip any O/L devices as it loses it power with timeclock dropping out.... all this can be tested for by running say override option an having a meter on the timeclock supply and watch if the voltage drops when timer relay opens. As i said its just a guess and one of many possibilities.

 

[monjoor]

Timer has direct mains connected, spoke to psu manufacture. They say its the voltage/current fluctuation caused by my load that is causing the voltage dip to knock out the timer.

With the slightly larger psu there seems to be no issue.

 

[Darkwood]

Well it adds to your experience and now something to look out for and a lucky guess from me I may add .. just be wary in future about switching multiple inductive loads on together of which the driver packs on LED's are notorious for a large spike on power up... always try to switch in banks or time delay if auto one bank from the other.

 

[monjoor]

Thanks again for your help!