TRIAC Dimmer/Controller

[Jack// ani]

triac dimmer

Hi all,

Why do TRIAC based motor speed controller and lamp dimmer reduces the life of motors/lamps?

Thanks

 

[IanP]

u2010b schematic

There is always answer out there:

Power harmonics caused by dimmers
All phase control dimmers are non-linear loads. A non-linear load is one where current is not in proportion to voltage. The non-linear load on dimming systems is caused by the fact that current is switched on for only part of the line cycle by a phase control dimming system. This non-linear load creates harmonic distortion on the service feeder.

Harmonics are currents that occur at multiples of the power line voltage frequency. In Europe where line frequency is 50 Hz the 2nd harmonic frequency is 100 Hz; the 3rd harmonic is 150 Hz, and so on. In North America where line frequency is 60 Hz the 2nd harmonic frequency is 120 Hz; the 3rd harmonic is 180 Hz, and so on.

Excess harmonic currents cause conductors and the steel cores of transformers and motors to heat. Odd-order harmonic currents (specifically the 3rd harmonic) add together in the neutral conductor of 3 phase power distribution systems. The 3rd order harmonic current present on the neutral is the arithmetic sum of the harmonic current present on the three phase conductors (this also applies to the 9th, the 15th and so on harmonics). Harmonics could theoretically elevate the neutral current to 3.0 times what is present on a phase conductor. With typical phase control dimming system connected to three pahse feed, the harmonics normally elevate neutral current to about 1.37 times phase current. If the wires are not properly rated for this, neutral conductor overheating or unexplained voltage drops can occur in large dimming systems.

Rest on dimmers you can find here:
https://www.epanorama.net/documents/lights/lightdimmer.html#basics
Regards,
IanP

 

[Jack// ani]

triac dimmer controller

Thanks IanP. I’ve one confusion…I’m asking for a single phase induction motor. Harmonics frequency components offers a higher inductive reactance as compared to the line frequency (XL=2pi*fL). Higher inductive reactance means lower current, then why is here excess heating effect?

Will a reverse phase controlled, motor controller based on IGBT or Power MOSFET be effective solution? Will it improve the overall efficiency/life of the motor? Please suggest some idea/schematic

Thanks

 

[IanP]

triac controller

The higher frequencies cause additional watts loss and heat to be dissipated by the iron of the motor, while the higher currents cause additional watts loss and heat to be dissipated by the copper windings of the motor so the actual mechanical ability of the motor is reduced, as the watts are expended as heat instead of as mechanical power. Similar thing with transformers..
Look what happens with the RMS current whenever harmonics are present: example: 100%fundamental current+100% harmonic current = 141% RMS current..
Reverse phase control claims to significantly improve elimination of harmonics.
By how much?
I don't have much experience with reverse phase control..
Regards,
IanP

 

[prabaa8]

inductive reactance dimmer

hi i need to interface with u2010b and T2117 could me hlp mout?