How to reduce flow rate?

[Hon]

Benz,

What happen if the motor is a DC motor? Eg. An AC/DC transformer is empolyed to convert the AC supply to DC in order to driver the motor. If we apply phrase angle control and manipulate the freq on the AC end thus say reduce the freq to 25hz. What will happen at the ac/dc transformer end and what is the final voltage or running power of the DC motor?

[Benz...]

After so much of technical staffs, can I confirm whether household fan switch can be used to control pump's speed?

IMHO.... cannot....

cos i think that the motor that drives the fan is a dc one... your home ac input goes to a diode which then coverts it from ac to dc lor... and then by controlling the voltage.. you control the fan speed... will check it out and let you know ya....

[Benz...]

Benz,

What happen if the motor is a DC motor? Eg. An AC/DC transformer is empolyed to convert the AC supply to DC in order to driver the motor. If we apply phrase angle control and manipulate the freq on the AC end thus say reduce the freq to 25hz. What will happen at the ac/dc transformer end and what is the final voltage or running power of the DC motor?

Hon,

if your pump motor is dc driven, and your input is ac.. then like i reckon that what the OEM does is to run it thru a diode which then "converts" your ac to a dc.. i.e. half of a sine wave... if this is the case.. speed of the motor then depend on the voltage applied.. if you were to control the frequency... hmm.. now thats a tot.. i need to find out more.. will get back to you on this one... but if you have a dc driven thru a ac/dc convertor.. then no need to bother abt the incoing frequency lor..

if you were able to play ard with the frequency of a ac motor, then yes you can control the speed of the motor but then i have not heard of halving it before... the most i have seen on a controller (frequency) is only +/- 15Hz... this is only applicable if your motor is ac driven...

[Crab]

Benz,

What happen if the motor is a DC motor?  Eg.  An AC/DC transformer is empolyed to convert the AC supply to DC in order to driver the motor.  If we apply phrase angle control and manipulate the freq on the AC end thus say reduce the freq to 25hz.  What will happen at the ac/dc transformer end and what is the final voltage or running power of the DC motor?

I don't think that will affect the output of ac/dc transformer/power supply. I've made quite a few variable power supply so far. One of them is to drive a DC 12 V pump.

A good ac/dc power supply has 3 main basic steps. Frequency input in diagram 1 will not affect the output in diagram 4.

[Crab]

Probably I'm too shallow. Are you talking about running from a one diode ac/dc transformer?

[cmswong]

Hi guys,

Two months ago ,PraticallyI had hook up a fan speed controller on tunze stream 6080.The controller is clipsal come with a minimal preset and a variable control.I able to reduce abit because due to the

stream design its off balance if too slow.Variable control can still control the speed .But for pump I think its can do better.I hope this info would help.

[Crab]

CMSWong,

Thanks for sharing. Any risk of fire or explosion? I'm thinking of trying on Eheim 1060.

[Cookiemunster]

I have been working on a design to control multiple AC powerheads. Will let you know how it works.

The method Tunze makes its life easier is it uses DC pumps which I mentioned in my previous post that

Guys,

DC pumps control speed by varying the voltage. Changing frequency will damage the pump.

AC pumps control speed by varying frequency. Changing voltage will damage the pump.

DC pump speeds can be controlled easily using a variable resistor to adjust the voltage and this is how TUNZE works on. If only DC pumps were cheaply and commonly available. It is alot safer too.

However there is a reason why our common powerhead and pumps for aquarium uses DC. The reason being it is more energy efficient to use AC for motors than DC. Also heat tends to build up faster in a DC motor than a AC motor. And the circuitry for a AC pump is alot simpler than a DC pump as no transformer is involved hence meaning cheaper pumps.

[Crab]

I have been working on a design to control multiple AC powerheads. Will let you know how it works.

Thanks cookiemunster. Looking forward to your update.

[cmswong]

Hi crab,

I had it runing for more than 1/2 hr and I am sure it will be quite safe.Because you are not altering the freq. The motor and controller did not heat -up.If wiring is correct everything should be O.K.