Digital timeclock back up facility (Non Diy)

[333rocky333]

Not reallly Diy but apreciate some advise.

We do some work for a large supermarket and there car park lights are usually on all night and go off during daylight.

However to save money they wanted some going off early during the night.
Another company has fitted digital timers in each post to do this.

I assume theres some sort of electronics in the clock which maintains the memory.
Please does anyone know whats in them and whether by losing power for about 8 hours a day would have any adverse effect on the timeclocks.

Many of them seem to be failing lately and just wondered why.
Thanks in advance

 

[RedHerring2]

Many of them seem to be failing lately and just wondered why.
Thanks in advance

What's failing, the lights or the time clocks?

I'd suggest that you ask in the electrics forum.

 

[333rocky333]

Yeah sorry, not sure how it got here, ive asked the mods to move it.
Its the clock failing

 

[bernardgreen]

Losing power for 8 out of 24 hours should be survivable if there is a decent sized back-up battery to keep the real time clock running when power is off. The small battery in a PC can keep the PC's clock running for a few years without power.

Look at the clock's displayed time. If it is still correct then the back up battery is probably OK and the fault is possibly in the output circuit switch of the clock that control the power to the lamp. Lamp wattage may be too much for the clock's switch or ( often happens ) the wattage is not too high but the in-rush current when the lamp turns on burns out the switch.

 

[joinerjohn]

Surely the digital timers are permanently connected to the mains supply and only turn the lights off and then back on? Or am I missing something here?

 

[333rocky333]

There only small one module dinrail mounted timers, the battery couldnt be too big.
im quessing it may be an electronic circuit rather than a battery, but not got one to open.

 

[333rocky333]

Surely the digital timers are permanently connected to the mains supply and only turn the lights off and then back on? Or am I missing something here?

Normally yes, but they are already supplied by the main timer and photocell, so lose power daily during daylight, the new timers are too provide, early off to just some.

 

[flameport]

Timers in each post is a poor design, and even more so if the power to each post is also switched elsewhere. Regardless of the type of timer, if they are without power for hours every day, problems are inevitable.

 

[ricicle]

Lately I've been using Theben Top2 din-rail timers and the battery is claimed to last 10 years ! Not sure how the battery life would be affected by regular power outs.

 

[RF Lighting]

Are you saying there's a main photocell and contactor somewhere and the coloums are supplied with a switched live only?

If so that is very poor design. Why not just interrupt one of the switched lives at the contactor place?

I'm not aware of a time clock which would do this having never needed to!

 

[333rocky333]

Are you saying there's a main photocell and contactor somewhere and the coloums are supplied with a switched live only?

The contactors are double pole so a switched L and a switched N
through an energy management system similar to a Trend system, and remotely linked to H/Q

If so that is very poor design.

Not really whys that, how else could they control it remotely.

Why not just interrupt one of the switched lives at the contactor place?

The way the circuits are wired it would leave dark areas, only certain lights need to go off and some need to remain on all night

I'm not aware of a time clock which would do this having never needed to!

I cannot see a problem with the way they have done it, though it dont seem right, or an alternative way, but im not sure what affect it has on the clock electronics.
However i do think switching the 400w M/H lamp might degrade the switch contacts over time.

 

[JohnW2]

Are you saying there's a main photocell and contactor somewhere and the coloums are supplied with a switched live only? If so that is very poor design.

Poor design? I think I must be missing something - prior to this new (fairly unusual and presumably not foreseen) requirement (for some lights to have additional switching) wouldn't that have been the normal and obvious way to do it? Unless there is a good reason, one doesn't normally supply an unswitched live, as well as a switched live, to a load which is remotely switched, does one? What would be the point?

Kind Regards, John.

 

[ericmark]

As you say all the clock needs to do is switch off half an hour after closing and one half an hour before opening. However my cheap home thermostat with clock is battery operated and I find when the batteries get near to flat it will stop working even though battery indicator says it's OK.

I would guess the batteries on these are not primary cells but secondary cells and the question is are they getting power for long enough to stay charged? Likely the contacts are powered on and no power off so will be using power all day. Maybe they could be programmed to be off 10am to 3pm so saving batteries?

 

[ColJack]

wouldn't a "delay off" timer have been more appropriate?

simply comes on when they rest of the lights do then switches off after x amount of hours?

or do they want them off at a specific time and back on again early? ( IE off at midnight but back on for 5am until switch off? )

 

[ban-all-sheds]

Normally yes, but they are already supplied by the main timer and photocell, so lose power daily during daylight, the new timers are too provide, early off to just some.

It's like that old joke -

"Can you tell me how to get to...?"

"If I were you I wouldn't start from here."