3 Phase timer switch

[seza]

Hi all,

This is a great forum, a big thank you to all those that made it possible,

I hope you good people can help me:

I have a 3 phase 10HP pump that I would like to turn on/off with a timer switch over a weekly program,

looking online I can not find much other than some Chinese device,

one idea was suggested to me was to use a contactor with a coil and timer switch that will act on the coil
to turn it on/off?

can someone please suggest an easier simpler cheaper way of achieving my aims - perhaps with links as to where I can buy the required kit?

Many thanks

 

[plugsandsparks]

Simplest is contactor and a simple single channel central heating timer to switch the coil of the contactor. central heating timers typically have a 7 day programme with lots of options for switching on and off at specific times.

 

[Timbo]

Wot 'e sed!^^^^^
Having been involved in heating system controls for nearly 40 years, the standard way is a 3 or 4 pole contactor with a 230v coil controlled by whatever timer that you fancy/suits your needs.

 

[seza]

ok thanks guys, that confirm what I was told before.

 

[pc1966]

As above, some standard timer and a contactor.

10HP is a fair bit of motor to switch. Depending on the starter (star-delta or DOL) you might be needing a contactor rated at 63A or so to meet the switch-on surge. Check the contactor data sheet as they typically give several switching limits with the headline being the most favourable for a simple resistive load (e.g. heater).

 

[seza]

Thanks Pc1966, I was looking at the rating of some contactors, 63A was one of them.

 

[Lucien Nunes]

You'll need a contactor with an IEC AC-3 rating comfortably over 16A (AC-3 loads include squirrel cage motors) or an IEC power rating of 7.5kW or more. These rating take into account the starting current of the motor and are lower than the thermal or AC-1 rating of the contactor, so they don't need to be inflated. Most timers have a limit of 250V on their output contacts so the coil will need to be 230V. This assumes your supply has a neutral - some motor circuits don't if the existing switchgear doesn't require one. Confirm that before you start ordering!

But...
What switchgear / starter is in use at the moment? Is it D-O-L? Could the timer be connected into that? If the existing starter has NVR, you need to consider the effect of adding an outboard contactor.