4000w dimmer + 8 inch PSC fan - How to remote control it?

A_falstad-image.md

Links to devices:

• Dimmer: '4000w' Motor controller (AC triac dimmer)
• Control Knob: Mains 'insulated' 2W 500K WTH118-1A Potentiometer
• Load: 220v 180w PSC Fan Motor Vortex Pro 8 Inch

Problem 1 (solved):

• Dimmer circuit works to control motor speed adequately... BUT
• Everything is LIVE, and I want to control the dimming remotely, via ESP32 / or similar Wifi MCU
• So ideally I would like to replace the WTH118 potentiometer with something else (perhaps an opto somehow?) IDK

This will be solved by:

• Switching in and out a group of 4-5 relays. Connected in series with the speed control potentiometer.
• The relays switch in and out a resistor ladder arrangement.
• The resistor ladder is 4-5 68kOhm 5 watt resistors (750v rated).
• Then with an ESP8266 to control the relays remotely (over wifi). To get around the mains safety issue.
• This seems about right level of granularity to control the fan speed well enough for this specific device and the fan load in question.
• What was the existing 500kOhm potentiometer for the speed control remains in place. However it now acts as a bias control, to set the optimum 'in-between' level. So that the fixed resistance choices are well tuned and the most effective.

Problem 2:

This is where I currently need some further assistance / guidance

• Switching tansients, when triac comes on / off during the middle of the cycle
• It causes some 50hz clicking, and spikes / noise. And is probably not good on the PSC motor or its 6uF cap.

So how best to solve?

• Perhaps this issue it's either 'not fixable' when a triac is the thing doing the switching? Vaguely have gotten this impression.
• Otherwise I do not know how to add an effective 'snubber' arrangement, around this PSC motor. Because it's not a simple load, including the 6uF cap, etc.
• In fact there are many different types of snubbers when searching online. No idea how to narrow it down.
• If can get any 'decent hints'. Then with a shorter list of fewer options to investigate... then we can be in a position try them out in the falstad circuit simulation. Which appears to be modelling the real world behaviour 'pretty good' ATM.

Image:

Working circuit is being modelled in falstad.com circuit simulator. And it appears to be working! Copy-paste text below the image with "File --> Import from text"...

falstad-circuit.txt

$ 1 0.000019999999999999998 12.050203812241895 99 5 48
w -16 96 -16 0 0
w -16 96 -16 288 0
d 80 160 144 224 3 default
d 80 288 144 224 3 default
d 16 224 80 160 3 default
d 16 224 80 288 3 default
w 256 112 256 32 0
w 256 320 176 320 0
w 16 224 16 416 0
w 144 224 176 224 0
w 16 416 176 416 0
w -144 0 -16 0 0
w -448 -240 -144 -240 0
v -448 592 -448 -240 0 1 50 320 0 0 0.5
206 -144 -240 -240 0 0 0.05 0.05 10 true
w 256 320 336 320 0
w 336 256 336 320 0
174 256 192 336 304 1 500000 0.5792 Control Knob, Slider at 0 Ohms = Full ON, Slider @ 500K = All OFF
r 256 112 256 192 0 4760
r 176 224 176 320 0 33600
r 176 320 176 416 0 33600
c -16 -128 -16 0 0 1.0000000000000001e-7 -0.7664605687743631
r -16 -240 -16 -128 0 4760
203 -256 -96 -256 32 0 500 100000000 32 0.01
w -16 0 880 0 0
w -256 -96 -176 -96 0
c -256 32 -16 96 0 1.0000000000000001e-7 -1.3344057621362708
w -144 -240 -16 -240 0
w 256 32 -128 32 0
w 80 288 -16 288 0
w -256 32 -128 32 0
w -256 160 80 160 0
w -448 592 720 592 0
403 -512 208 -224 336 0 13_16_0_20483_640_6.4_0_2_13_3
w -16 -240 336 -240 0
w 336 -240 336 256 0
w -256 32 -256 160 0
w 1040 560 1152 560 0
x 733 549 750 552 4 24 N
x 853 43 866 46 4 24 L
w 880 32 880 0 0
w 1152 32 880 32 0
c 1040 400 1040 496 0 0.000006 2.2737367544323206e-12
l 960 304 880 208 0 0.15 -3.49763486278173e-16
r 1040 400 960 304 0 55
r 720 400 800 304 0 51
l 800 304 880 208 0 0.16 0.047024128325579256
w 880 64 880 208 0
w 720 496 720 592 0
w 720 400 720 496 0
w 1040 496 1040 560 0
w 880 32 880 64 0
b 627 58 1126 524 0
x 645 120 833 123 4 24 PSC\smotor\s0.8A
x 644 91 836 94 4 24 8\sinch\sHVAC\sfan
x 643 148 791 151 4 24 220v\s/\s180w
x 996 274 1090 277 4 14 phase\sshifted
x 677 273 756 276 4 14 main\s/\s'run'
x 688 292 742 295 4 14 winding
x 992 259 1091 262 4 14 'start'\swinding
x 1005 288 1082 291 4 14 by\s6uF\scap
x 884 82 955 85 4 14 black\swire
x 1046 488 1123 491 4 14 brown\swire
x 732 511 796 514 4 14 blue\swire
w 1152 560 1152 32 0
b -367 -323 516 522 0
x 638 -61 1169 -58 4 24 https://www.amazon.co.uk/dp/B0749MSDQX
x -365 -337 296 -334 4 24 https://www.aliexpress.com/item/4000810406219.html
x -368 -369 615 -366 4 24 4000W\s0-220V\sAC\sSCR\sElectric\sVoltage\sRegulator\sMotor\sSpeed\sController\sDimmer
x 637 -93 963 -90 4 24 Load:\sVortex\sPro\s8\sinch\sFan
x -350 -260 -249 -257 4 24 Input\s(L)
x 368 -13 491 -10 4 24 Output\s(L)
403 528 -304 1072 -160 0 24_16_0_4099_640_6.4_0_2_24_3
x 263 384 371 387 4 24 500K\s2W
x 263 408 373 411 4 24 Insulated
x 260 433 430 436 4 24 Potentiometer
x 264 358 419 361 4 24 Control\sKnob
x -436 576 -304 579 4 24 Neutral\s(N)
x 170 476 498 479 4 24 WTH118-1A\sPotentiometer:
x -353 503 497 506 4 24 https://www.finglai.com/products/relays/relay-accessories/WTH118-1A/
x -437 642 -331 645 4 24 Problem:
x -307 646 449 649 4 24 Dimmer\scircuit\sworks\sto\scontrol\smotor\sspeed\sadequately...\sBUT
x -309 672 832 675 4 24 Everything\sis\sLIVE,\sand\sI\swant\sto\scontrol\sthe\sdimming\sremotely,\svia\sESP32\s/\sor\ssimilar\sWifi\sMCU
x -310 698 1070 701 4 24 So\sideally\sI\swould\slike\sto\sreplace\sthe\sWTH118\spotentiometer\swith\ssomething\selse\s(perhaps\san\sopto\ssomehow?)\sIDK