Upgrading Capacitor-Based Fan Regulators for 500-1000 Watts

[Phyreg]

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A capacitor based fan regulator is rated for maximum 100 watts. What components need to be replaced to make it suitable for 500 watts or 1000 watts?
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[berkeman]

Summary:: Increase rating

A capacitor based fan regulator is rated for maximum 100 watts. What components need to be replaced to make it suitable for 500 watts or 1000 watts?
https://www.google.com/imgres?imgurl=https://i.pinimg.com/originals/67/fc/30/67fc30d4247cd8d3b5bab818d21d53be.png&imgrefurl=https://www.pinterest.com/pin/719942690421853396/&tbnid=H-pgcFdZtPGdMM&vet=12ahUKEwiXrdDHhpHyAhWzGbcAHfxUCp0QMygAegUIARCgAQ..i&docid=PqrUvf_S83PntM&w=918&h=617&q=capacitive fan regulator circuit&ved=2ahUKEwiXrdDHhpHyAhWzGbcAHfxUCp0QMygAegUIARCgAQ

Welcome to PF.

Maybe change the motor? Have you downloaded typical datasheets for the capacitors shown in the schematic? What specification in the datasheet should you look at to figure out the power handling capability of the "regulator"?

 

[Baluncore]

What components need to be replaced to make it suitable for 500 watts or 1000 watts?

First you must replace the fan. The capacitors are being used as series reactance to restrict the voltage reaching the fan motor. The values of capacitance would need to be increased, but there are regulations to follow, and high voltages to avoid, so it is not that easy to give details.

 

[Phyreg]

Thank you for quick response. Changing the motor is not an option for me. 100 watt was printed on the regulator. I thought replacing the capacitors and resistors with higher wattage caps and resistors should increase the max load capability of the regulator. Is that incorrect?

 

[jrmichler]

I have worked with these type of regulators. They are designed for use with a particular size and type of two phase motor used in ceiling fans.

replacing the capacitors and resistors with higher wattage caps and resistors should increase the max load capability of the regulator.

This will not work. We need to know exactly what kind of load is drawing 500 or 1000 watts - is it a resistive load, lights, or a motor? If lights, what type of lights? If a motor, what type of motor, including a photo of the nameplate.

 

[Baluncore]

Changing the motor is not an option for me.

The fan motor is probably rated at 100 watt. You will not get more power than that since at maximum speed the regulator is a short circuit.

You must get another motor, and another fan blade, and another regulator.

 

[Phyreg]

I should have provided more details in the beginning. Regulator is rated for 100 watt at 240V 50Hz and is designed for ceiling fan. However, the concerned motor is a single phase 93 watt at 240V, 1/8 HP multi speed motor used in either pedestal fans or room coolers. It has a capacitor for starting torque but also has 4 wires coming out of it for low, medium, high speed and one common. A rotary switch is used to adjust speed. Fan is too fast even at the lowest speed so I believe a regulator in series might be useful. I am not sure whether 93 watts will be consumed at lowest speed or highest. Regulator should work because 93 watt load is lower than the regulator's max capacity, but only just. Therefore I wanted to increase the max capacity of the regulator, so that it lasts longer. 500 watts, or even 200 watts should be sufficient. 1000 watts would probably be overkill.

Do I need to replace just the capacitors, or even the resistors? And by how much? And what factors decide the max capacity of a regulator? Or is it just an approximation? Please tell if more information is needed.

 

[Baluncore]

Fan is too fast even at the lowest speed so I believe a regulator in series might be useful. I am not sure whether 93 watts will be consumed at lowest speed or highest.

You need to reduce the value of the capacitors, to slow the fan down.
The parallel resistors are there to discharge the capacitors when not in use.

Regulator should work because 93 watt load is lower than the regulator's max capacity, but only just. Therefore I wanted to increase the max capacity of the regulator, so that it lasts longer.

Increasing the power is not possible without changing the motor, increasing the voltage of the capacitors may increase reliability, but how many times has the controller failed and needed repair?

 

[jrmichler]

The 100 watt rating of the regulator tells you what size motor it is intended to be used with. It has nothing to do with the durability of the regulator. If you put a 1000 watt regulator of this type on a 100 watt motor, the motor would run full speed regardless of the knob position. If you put a 10 watt regulator of this type on a 100 watt motor, the motor would probably not turn at all, but the regulator would not fail.

That is because the regulator puts various size capacitors in series with the motor. The size of the capacitor controls the motor speed, but only for certain motors. The durability of this type of regulator is determined by the quality of the switch and quality of the capacitors.

Are you sure that the capacitor is a starting capacitor? If so, that motor will probably not work with any speed controller. If it's a run capacitor for a two phase motor, it might work. Try connecting your regulator to the 93 watt motor. If it does not work, it's because that motor is of a design that does not work with that type of speed regulator.

Other types of regulators, such as continuously variable SCR light dimmers, are different. Different rules apply to those.

 

[Phyreg]

Okay. I connected the regulator in series. It worked but the speed control was not satisfactory. The second highest option reduced the speed so much as if it was the lowest speed.

Q1: This is probably because it was designed for different weight and load in mind?

Q2: If I connect another capacitor based regulator rated 80 watts in parallel with the 100 watt regulator, set the speed to second highest in both, will it slightly increase the speed as compared to the second highest one of just one regulator?

Q3: If I use a triac-based-dimmer to achieve the satisfactory speed, will connecting a 100 watt capacitor based regulator in parallel with the triac-based-dimmer, with the second highest speed setting of the capacitor based regulator, improve the power factor and reduce the rubbish sound at low speed? The dimmer is rated for 400 watt load by the way.

 

[jrmichler]

Q1: Probably yes.

Q2: Probably more than slightly. Easy enough to run a test and find out.

Q3: Triac-based dimmers are not designed to work with inductive loads, such as motors. Or in parallel with capacitors. It might work, it might not work, or it might destroy the dimmer. Test this only if you are willing to throw away the dimmer if it does not work.

Side note: I once tried to control the current through a resistance wire using a dimmer. It did not work, no smoke came out, but the dimmer was destroyed.