What relay I have to use ?

I want to control a 440V 3 phase 30A pump using a relay. Which Industrial grade relays can I use ? Is it better to use 3 Pole electromagnetic relays or should I use Crydome Solid State Relays ? If Solid State relays are used I thing the cost will be more and I also have to use a heat sink with a cooling fan and a temperature sensor to sense the relay temperature and control the cooling fan using PWM.

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Cost is not important to me. I can use either Crydom or Schnieder SSRs. They system is a GSM based PUMP control for farmers. The pumps are turned ON/OFF two times a day atmost. At some places the farmers have to walk 1 km to turn ON/OFF the pumps. I want to know if there is a Single SSR which controls the 3 phases. My pump rating is 440V 3 phase. I am thinking about using SOLICON DRC Series series of Crydom relays which is rated for 510VAC 30A. Do I need any special means to drive the SSRs ? If there is an Single SSR which can control 3 phases then I will make a system which have option to control 8 pumps.

you can use contactor for controlling the 3 phase pump.SSR can do it but it is costly.For controlling SSR or Contactor you need use ULN2008 driver or transistor after micro controller pins.some protection circuit like snubber from controlling arching of contactor or relay(SSR).

I think there will be no arching in SSRs. I will be using 2 KV MOVs on contacts of SSR to protect the SSR from surges. I need to control a 10 hp 3 phase motor. What will be the price range for a good Contactor ?

What about this contactor ?

http://www.globalspec.com/specsearch/partspecs?partId={9D8DF549-44F4-4664-9CC9-6F95786D7BB9}&vid=168903&comp=1439&regevent=new&pubsubscribe=1&alertsubscribe=1

Please provide info about snubber design. Is Contactors better or SSRs ? The above contactors control voltage is 208. So, I I will not be able to control it using MCU. Is there any contactor which can be controlled using a MCU ?

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Please provide info about snubber design. Is Contactors better or SSRs ? The above contactors control voltage is 208. So, I I will not be able to control it using MCU. Is there any contactor which can be controlled using a MCU ?

If I use the above Contactor then do I have to use 1 5V DC Coil, 230V 1A Contact PCB mount relay to control the control voltage of the contactor ?

If I use the above Contactor then do I have to use 1 5V DC Coil, 230V 1A Contact PCB mount relay to control the control voltage of the contactor ?

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sorry your link need requires registration so i didn't find info about contactor you refer.But block diagram of controlling contactor is controller pin--> driver transistor-->12V DC or 7 amp general relay ---> contactor energizing pins--->contactor output to 3 phase motor or pump

snubber comes different value you need calculate your resistor and capacitor value

If I read your numbers correct we are talking about a 22kVA pump here, and I suppose you don't just use a contactor to start that with a kick? What about adding a softstarter? Most industrial softstarters can be controlled by a low power control input.

In my design there was starters already and my Contactor would get input from output of starter. Are there softstarters which can be turned on using microcontroller with or without ULN2003A ? If yes, who is making such a starter ? The make should be good like Schinider. If there are soft starters which have control pins which can be connected to MCU then I will omit Contactor, relay or SSR and just use SoftStarter in that place. Provide link for SoftStarter which can be controlled by MCU and which can handle a 40 HP pump.

Industry standard soft starters are controlled by either contact closure or 24V DC. The best way to control it from 5V logic is a small relay.

The pumps are turned ON/OFF two times a day atmost.

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A soft starter for a 30 HP motor is an expensive device and would be only used in case of particular need like unusual high number of start/stop events or if start torque limitation is required to protect the drive.

The application specification in post #1 clearly suggests a classical wye-delta contactor starter.

I checked and found that a good quality softstarter for 40 HP pump will cost USD 1500. I think contactors are cheaper. I need 3 pole or 4 pole contactor which can be turned on with 12 or 24V DC and which can handle a 40 HP pump. Do ABB or Legrand or Schnieder have such contactors ?

All major automation manufacturers have suitable contactors. Standard coil for 30 kW/40 HP is still 230 VAC. It has the advantage of requiring less power in continuous operation, but 24 VDC should be available from most vendors as well.

I keep my previous comment that wye-delta is preferred over direct start in this power class.