have a very small metering pump that runs on 120VAC and Current of 1.4A with a max output of 250 PSI. Due to the size, what is a good relay and starter size that it will need irrespective of the distance between power source and point of installation which h gives a negligible VD.Asking cos this is a very small pump..
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small metering pump spec
- Thread starter EEENGRX
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- #2
I don't see using a motor starter for that small a motor. It should be internally protected.
I would look at relays in the 10 Amp, 250 Volt range.
Possibly plug-ins with din rail mount sockets.
I would pick a 10 Amp relay within my budget and look at the specs for any reason that it may be unsuitable.
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
I would look at relays in the 10 Amp, 250 Volt range.
Possibly plug-ins with din rail mount sockets.
I would pick a 10 Amp relay within my budget and look at the specs for any reason that it may be unsuitable.
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
- Thread starter
- #3
- Moderator
- #4
10 Amp relays are plentiful and cheap.
We don't know what type of motor you are using.
The rule of thumb for an induction motor is that starting current is six times running current.
The first cycle transient may more than double that.
A 2 Amp relay will work just fine, until it doesn't.
(Amazon will sell you 2 10 Amp relays with bases for $12.You may chose to spend a little more for better quality.)
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
Try it and see.
We don't know what type of motor you are using.
The rule of thumb for an induction motor is that starting current is six times running current.
The first cycle transient may more than double that.
1.4A x 6 = 8.4 Amps.
A 2 Amp relay will work just fine, until it doesn't.
(Amazon will sell you 2 10 Amp relays with bases for $12.You may chose to spend a little more for better quality.)
--------------------
Ohm's law
Not just a good idea;
It's the LAW!
- Thread starter
- #5
1.4A @ 115VAC puts it at somewhere around 1/10th HP. Most common relays are good for up to 1/2HP. A "motor starter" would be overkill for something this small.
Look at the motor nameplate (if you can), it should tell you if it is self-protected and if so, you do not need external OL protection. It may say "Thermally Protected", it might just have a "TP" on the nameplate, or it might say something like "impedance protected", meaning it is designed to avoid starting a fire even if the motor is stalled indefinitely. A number of small 115V metering pumps I have connected have been impedance protected.
" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden
Look at the motor nameplate (if you can), it should tell you if it is self-protected and if so, you do not need external OL protection. It may say "Thermally Protected", it might just have a "TP" on the nameplate, or it might say something like "impedance protected", meaning it is designed to avoid starting a fire even if the motor is stalled indefinitely. A number of small 115V metering pumps I have connected have been impedance protected.
" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden
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