Time delay relay suggestions?

I'm looking at changing a 1 HP pool motor to a two speed motor to save energy. A motor running at half speed can move the same amount of water using a lot less electricity. The problem is the system has a solar heater and from researching online it appears that there is a good chance that the pump will need to start on high speed to get it flowing, then it can switch to low speed to keep it going.

So, the question is, any suggestions for an appropriate 240V time delay relay, ie a relay where there is either a fixed or adjustable time delay of about a minute? I've looked online and there appear to be a lot of them, but they are either for rack mounting or else they have some kind of pins that then plug into a socket. I guess I could find a socket, figure out how to mount it, etc, but I was wondering if anyone knows of a relay better suited to easily mounting/wiring into a typical electrical box? Will need a box for a low/high switch and looking for something that could easily go in there. I may not need it if it will get going on low, but figured it's kind of slow here lately and might as well be prepared.

TIA for any help.

Reply to
trader_4
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A lot of these that can use a socket, also have a threaded base that accepts a screw so you can mount them just about anywhere and the pins for the socket will take a regular spade connector.

Reply to
gfretwell

I'm not opposed to using a socket and agree it has advantages. It's just that I'm not familiar with the socket, where you'd get it, how it can be easily mounted inside a typical weatherproof electrical box, etc. I just thought if there was some relay module type thing, with wires or screw terminals, it would be easier to deal with.

I looked on Ebay a bit. And there are relays, some even come with a socket, so that would solve the socket problem. But so far, I haven't found one that's 240V coil, 240V contacts, rated for 1hp, etc. One problem there is that have thousands of them and they aren't organized so it's hard to wade through them all. There are a lot of cheap ones from China that even come with a socket, but they are only rated for 5A.

Reply to
trader_4

On 4/18/2014 12:34 PM, trader_4 wrote: ...

What kind of a budget do you have here?

Newark and/or Mouser will be able to supply what you're looking for, but it's likely $100 min for the rating.

The cheapest I found in a very quick perusal at

Reply to
dpb

Single or two phase motor?

Reply to
Nicky Tesla

I am sure it is a single phase motor if he is going to use it on the US grid. I bet you meant 120v or 240v. ;-)

Reply to
gfretwell

I think I would just try it first before I changed anything. My 2 speed spa pump gets the water up to the solars on the 1/10th HP speed. I was thinking just like you but I figured out it was working without it. It does take a few minutes to actually get the flow going but once it does, it works fine. The pump is not cavitating or running dry, it is just taking that long for the water at that head to get up there.

Reply to
gfretwell

Yes, I plan to try it without the relay first and figure it may work. I just figured I'd be further ahead if it turns out I do need it. And it's been kind of slow here, except for the political threads...

Reply to
trader_4

I was hoping for under $35, but if it turns out I need it, then even if it costs $100 it will still be worth it in money savings, just a longer payback....

That's the problem I was having on Ebay. Lots of cheap brand new ones for even $7, but they aren't rated for 1HP. I still think I could probably find something there, but gave up looking because there isn't anyway to quickly zero in on it, ie:

240V coil 240V 1HP contacts SPDT or better Delay ON ~1min

To find it you have to look through a lot of them and there are 1000s there. If it turns out I really need it, I can keep looking.

Reply to
trader_4

You could split the problem up and buy the appropriate double throw relay and use a 555 timer to kick it off for a minute or so

Reply to
gfretwell

Great minds must think alike. I was just back at Ebay looking and came to a similar solution. They have cheap $5 240V time delay relays that will switch a few amps. And I found a beefy regular 240V power relay for $17:

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So, worse case I can use one relay to drive the second relay. While not ideal, it may be hard to beat on price, < $25 total.

Reply to
trader_4

Trader_4 thinks 240v center tap is 2-phase service.

Reply to
Bubba

Doh! After posting the above, I realized it's DPST. I need DT, but the approach is still vaild, just need to find a SPDT or DPDT power relay.

Reply to
trader_4

Oh, is he the one? Went 'round and over that just a few weeks ago...

Reply to
dpb

On 4/18/2014 3:34 PM, trader_4 wrote: ...

...

If you're not wedded to the idea of the integrated delay coil, options for just the relay are much wider...

You can sort/search at Newark or Mouser

Here's

Coil >=120VAC Load >=230VAC, >=20A Contacts - DPDT

From $15 up depending on various other things...

Well, I was too lazy to go get the short URL but use the search engine at

I got 50 or so I think...

Reply to
dpb

I would first just try it on low speed and see how it works.

The cost and complexity of a time delay relay will probably not pay back.

Mark

Reply to
makolber

Since you want to bring that crap up all over again, let me say that I never called it two phase service. Just like I wouldn't call Kleenex soft white paper made from trees. But that's what Kleenex is and just as surely there are two phases present in a 240/120V service. That it's not commonly refered to that way from a power industry perspective, doesn't change what is physically there.

IEEE power system engineers agree:

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4520128

"Distribution engineers have treated the standard "singlephase" distributio n transformer connection as single phase because from the primary side of t he transformer these connections are single phase and in the case of standa rd rural distribution single phase line to ground. However, with the advent of detailed circuit modeling we are beginning to see distribution modeling and analysis being accomplished past the transformer to the secondary. Whi ch now brings into focus the reality that standard 120/240 secondary system s are not single phase line to ground systems, instead they are three wire systems with two phases and one ground wires. Further, the standard 120/240 secondary is different from the two phase primary system in that the secon dary phases are separated by 180 degrees instead of three phases separated by 120 degrees. "

So do electrical eqpt manufacturers:

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And if you disagree with them, perhaps you can answer the questions I pose in this simple exercise. Simple questions that no one on the other side of this will address, because they can't. Let's start with a 3 phase system. I have 3 phases and a neutral coming into a building. Everyone agrees there are 3 phases separated by 120 deg. Now let;s get rid of one. How many phases are there now? Two obviously. Now let's make the phase difference

160 deg between them, instead of 120. How many phases now? Still two? Now let's change the phase angle so that they are 180 deg apart. How many phases now? If it's not two, explain the magic that just happened. And if it is two, then adjust the voltages and you have a service that is identical to 240/120V split phase. The electrons flow exactly the same way and electrically it is indistinguishable from 240/120V split-phase.

QED

Reply to
trader_4

On 4/18/2014 7:20 PM, trader_4 wrote: ...

Which is _exactly_ what I tried to tell you some time back that you refused to heed. It's two separate uses of the word "phase".

Reply to
dpb

We just call them two ungrounded conductors, single phase.

Reply to
gfretwell

Cut some.

Would you mind using a pneumatic timer? We use 480v stuff at work sometimes so have to use a 480 contactor then attach some sort of timer to it. We usually get stuff from Crescent.

Reply to
Dean Hoffman

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