direct online starter switch and timer control

[paul copeman]

hi,

my customer has a direct on line starter (with green and red push buttons)

for his 0.75kw 1ph swimming pool motor but he doesn't want to have to switch it on and off himself

is it possible to get a starter that switches itself on and off via a timer

any help would be greatly appreciated

sparky paul

 

[Manator]

I doubt that it would comply with some regulations if fully automatic, I would consider the inconveniance of manual switching a low price to pay for control of the equipment.

 

[paul copeman]

yes i agree manator

i have tried to explain to the customer that the starter requires manually switching on and off but he wants it to come on half hour or so before he gets home at night etc

im thinking i could probably install a timeswitch so that he at least does'

n't have to switch it off when hes done with the pool in the evening

could i do that by installing a timeswitch in the ciruit before the starter so that it is live at the time he comes home from work then he can switch it on himself then at a preset time it will turn of the supply to the starter therefore turning off his motor

and am i right in thinking the contactor would de-energise when the power was cut in this way??

thanks

 

[Riggy]

I doubt that it would comply with some regulations if fully automatic, I would consider the inconveniance of manual switching a low price to pay for control of the equipment.

Which regulations prohibit fully automatic motor control?

 

[Riggy]

Assuming when he starts the pump all he does is press the start button (i.e. no levels to check, no valves to open, etc) and assuming your risk assessment shows no reason not to, then go for it.

Personally I'd disconnect the start button and retain contact and wire the time switch into the contactor coil circuit in it's place. Obviously you would keep the stop button, overload, ant other safety items in the coil circuit.

 

[Sidewinder]

paul c,

There are a few issues to overcome here.

Just quickly as my brekkie is nearly ready.

First you are going outside the remit of 7671, and into other control systems standards.

You are in a domestic situation so none of the workplace regulations apply, however, it must be safe.

If you use for example a central heating type timer, which is I think what Riggy is suggesting then this would not function correctly and would not be safe.

If this is the sort of timer suggested then the contacts will close at a set time and open at a second set time.

This would allow immediate re-start in the event of a power failure which could be unsafe, also, if the overload or stop button were activated when the timer where on demand as it were with the contacts closed, the starter would again instantaneously re-close, again unsafe as there would be no means of stopping the pump without removing the supply.

This could be achieved with two of these simple timers one in series with the overload and one in parallel with the start button.

However, is the motor single phase or 3, is the starter a 400V coil, where is the device located, what are the control and power side circuit protection devices, where is the control voltage derived?

Unfortunately to make this safe and compliant with guidance is not quite so easy.

 

[paul copeman]

thanks sidewinder

the contactor/motor are single phase device is located in pumop room just above the pump and protection is via mcb with an rcd as the main switch to that ccu

any thoughts

please could you verify for me what type of timers you recomend would two simple battery timers sufice

 

[Andy™]

you could leave existing DOL in place, feeding a second contactor. this contactor is controller by the timer. this way, if there is a power failure, overload, or any other kind of fault, then the first will trip and will not re-start unless you press the start button

 

[paul copeman]

many thanks andy

so the existing contactor powers the time switch and that in turn powers the second contactor???

is that what u mean mate or have i misunderstood u

 

[Andy™]

first contator out goes into 2nd in, 2nd out to equipment. timer feed from before contactor, so it has a permanent supply

 

[paul copeman]

and when the time comes for the timer to switch off it will automatically release the coil thus switching off motor?????

 

[Andy™]

and when the time comes for the timer to switch off it will automatically release the coil thus switching off motor?????

yes. timer will only operate 2nd contactor

 

[paul copeman]

[quote name='Andy

 

[Andy™]

power to motor must pass through both contactors. timer will need a perm supply so must be connected before any contactor

 

[paul copeman]

ok thanks

and the timer is wired in parallel with the startr button on the second contactor

 

[Andy™]

there is no start button on the second contactor. its jsut a contactor

 

[Pingu]

If the existing starter has a contactor, then timeclock control of the coil control / overload circuit is all that is required.

I have never seen manual control on domestic pools (OK exclude the 50 quid inflatables)

 

[paul copeman]

many thanks andy

i can crack on with it now

 

[Sidewinder]

Andy,

This would work, but I am not sure if I like it!

 

[Andy™]

Andy,This would work, but I am not sure if I like it!

why?