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
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.
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 <$50 is rated 1/2 hp 240V--
On Friday, April 18, 2014 2:36:39 PM UTC-4, dpb wrote:
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
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 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.
On Friday, April 18, 2014 5:08:53 PM UTC-4, Bubba wrote:
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:
"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:
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.
On Fri, 18 Apr 2014 05:41:36 -0700 (PDT), trader_4
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.
On Friday, April 18, 2014 4:14:31 PM UTC-4, firstname.lastname@example.org wrote:
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...
On Friday, April 18, 2014 4:51:15 PM UTC-4, email@example.com wrote:
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
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.
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
Load >#0VAC, > A
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...
On Friday, April 18, 2014 8:23:34 PM UTC-4, dpb wrote:
That I refused to heed? Good grief. Now the story changes. The issue
was never about two separate uses of the word phase. Go back to where it
all started. Someone claimed that you can't say that there are two
hot legs that are 180 deg out of phase with each other in a 240/120V
split-phase service. That is how it started. I posted my position,
backed up by the IEEE and the other sources, which agree that there are
two phases present. And I clearly said right from the
beginning that I would not call a 240/120V split phase service "two phase
service", because that isn't how it's commonly referred to. It's not
referred to as two phase, because from the power company perspective,
what comes into the house over those 3 wires originates from one phase
on their generating system. But that doesn't change what is electrically
there and that you can see on a scope.
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