Pond pump speed control

In uk.d-i-y Tim Downie wrote:
Is is possible to use a speed controller (like a light dimmer) with a small
pond pump?

I have a Bermuda 3000 (3000l/hr) submersible pump that's really a bit more
powerful than I need. The motor has a solid rotor that appears to be made
of a ferrite like material.

I know that speed controllers can cause overheating problems with some
motors but given that it's underwater with water bathing the rotor, I don't
imagine this would be a problem in this case.

In this case, simple speed controllers won't actually work, it'll stay at
a constant speed (3000RPM) until it stops working, and hums loudly.
Suitable speed controllers are going for around 40-50 quid on ebay.
Search on
inverter phase motor induction
on ebay, searching titles and descriptions.

Ian Stirling wrote:

In uk.d-i-y Tim Downie wrote:

Is is possible to use a speed controller (like a light dimmer) with a small
pond pump?

I have a Bermuda 3000 (3000l/hr) submersible pump that's really a bit more
powerful than I need. The motor has a solid rotor that appears to be made
of a ferrite like material.

I know that speed controllers can cause overheating problems with some
motors but given that it's underwater with water bathing the rotor, I don't
imagine this would be a problem in this case.


In this case, simple speed controllers won't actually work, it'll stay at
a constant speed (3000RPM) until it stops working, and hums loudly.

I am not sure about the following and it would apply only to mag drive
pumps.

The pump works because the magnet is forced to follow the rotating
magnetic field. When the pump is "dimmed" the field becomes weak and
will be unable to force the magnet to stay ahead of it. As the rotating
field passes the magnet it will slightly demagnetize the magnet. In
time it will weaken the magnet to the point that the impeller will not
work at all.

The same thing happens when you restrict the output and it causes the
impeller to slow down. If the field is strong enough to keep the magnet
in sync with the rotating field even with the restriction then this is
not a problem. But I do not think it is alway the case.

HTH



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In uk.d-i-y HTH wrote:
Ian Stirling wrote:

In uk.d-i-y Tim Downie wrote:

Is is possible to use a speed controller (like a light dimmer) with a small
pond pump?

I have a Bermuda 3000 (3000l/hr) submersible pump that's really a bit more
powerful than I need. The motor has a solid rotor that appears to be made
of a ferrite like material.

I know that speed controllers can cause overheating problems with some
motors but given that it's underwater with water bathing the rotor, I don't
imagine this would be a problem in this case.


In this case, simple speed controllers won't actually work, it'll stay at
a constant speed (3000RPM) until it stops working, and hums loudly.

I am not sure about the following and it would apply only to mag drive
pumps.

The pump works because the magnet is forced to follow the rotating
magnetic field. When the pump is "dimmed" the field becomes weak and
will be unable to force the magnet to stay ahead of it. As the rotating
field passes the magnet it will slightly demagnetize the magnet. In
time it will weaken the magnet to the point that the impeller will not
work at all.

The case is similar to when the pump is just started, or the impeller
is stalled.
Magnets in general only demagnetise if you exceed the maximum field.
They generally do the first time it does, not over time.
So, probably not.

"Ian Stirling" wrote in message
...

In this case, simple speed controllers won't actually work, it'll stay at
a constant speed (3000RPM) until it stops working, and hums loudly.
Suitable speed controllers are going for around 40-50 quid on ebay.
Search on
inverter phase motor induction
on ebay, searching titles and descriptions.

Well, in the spirit of experimentation (and 4 glasses of wine) I decided I
just had to try it. The lamp dimmer, in the best traditions of DIY, was
scavenged from the next door neighbours bin. I wired it up, tested it with
a lamp and then plugged a smaller version of the same pump in to it.

As you said,initially no change and then just a sudden cessation of pumping.
Maybe a smaller pump will be the easiest option.

Cheers.

Tim

On Sat, 22 May 2004 22:51:30 +0100, "Tim Downie"
wrote:


"Ian Stirling" wrote in message
...

In this case, simple speed controllers won't actually work, it'll stay at
a constant speed (3000RPM) until it stops working, and hums loudly.
Suitable speed controllers are going for around 40-50 quid on ebay.
Search on
inverter phase motor induction
on ebay, searching titles and descriptions.

Well, in the spirit of experimentation (and 4 glasses of wine) I decided I
just had to try it. The lamp dimmer, in the best traditions of DIY, was
scavenged from the next door neighbours bin. I wired it up, tested it with
a lamp and then plugged a smaller version of the same pump in to it.

As you said,initially no change and then just a sudden cessation of pumping.
Maybe a smaller pump will be the easiest option.

Cheers.

Tim

Lamp dimmers do ther job by chopping off the peaks of the power's sine
wave.

Run an electric motor through it and you're likely to get a fried
motor, assuming the dimmer doesn't overload and smoke first.

HTH, hope it's not too late for you. :-)
When you let the "go-smoke' out of electronics, they won't go anymore.

Mike


Mike Patterson
Please remove the spamtrap to email me.
"I always wanted to be somebody. I should have been more specific..."

In this case, simple speed controllers won't actually work, it'll stay at
a constant speed (3000RPM) until it stops working, and hums loudly.
Suitable speed controllers are going for around 40-50 quid on ebay.
Search on
inverter phase motor induction
on ebay, searching titles and descriptions.

Well, in the spirit of experimentation (and 4 glasses of wine) I decided I
just had to try it. The lamp dimmer, in the best traditions of DIY, was
scavenged from the next door neighbours bin. I wired it up, tested it with
a lamp and then plugged a smaller version of the same pump in to it.

I had the opposite result. I used a fan speed control which is just a
dimmer with a snubber to protect the triac. The speed changed just fine.
This was before I purchased the Kill-a-watt meter so I didn't measure
the energy usage.

On Fri, 21 May 2004 11:20:01 +0100, "Tim Downie"
wrote:

Is is possible to use a speed controller (like a light dimmer) with a small
pond pump?

I have a Bermuda 3000 (3000l/hr) submersible pump that's really a bit more
powerful than I need. The motor has a solid rotor that appears to be made
of a ferrite like material.

I know that speed controllers can cause overheating problems with some
motors but given that it's underwater with water bathing the rotor, I don't
imagine this would be a problem in this case.

Pace "Home Improvement", there is no such concept to a man as "too much
power". What you need is more pond...

--
Too much month at the end of the money.

Mail john rather than nospam...

"John Laird" wrote in message
...
On Fri, 21 May 2004 11:20:01 +0100, "Tim Downie"
wrote:

Is is possible to use a speed controller (like a light dimmer) with a
small
pond pump?

I have a Bermuda 3000 (3000l/hr) submersible pump that's really a bit
more
powerful than I need. The motor has a solid rotor that appears to be
made
of a ferrite like material.

I know that speed controllers can cause overheating problems with some
motors but given that it's underwater with water bathing the rotor, I
don't
imagine this would be a problem in this case.

Pace "Home Improvement", there is no such concept to a man as "too much
power". What you need is more pond...

--
Too much month at the end of the money.

Well put.

On Fri, 21 May 2004 17:35:43 +0100, John Laird
wrote:

--
Too much month at the end of the money.

I couldn't have said that better.