# Speed control dial does nothing on VFD (SOLVED) & VFD wiring

**URL:** https://forum.onefinitycnc.com/t/speed-control-dial-does-nothing-on-vfd-solved-vfd-wiring/12831
**Category:** Spindle/VFD (Aftermarket/Unsupported)
**Created:** [May 1, 2022, 9:04pm UTC](https://forum.onefinitycnc.com/t/speed-control-dial-does-nothing-on-vfd-solved-vfd-wiring/12831 "2022-05-01T21:04:11Z")
**Posts on this page:** 1
**Showing post:** 17

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### Author: ![349iq2345](https://avatars.discourse-cdn.com/v4/letter/3/bb73d2/32.png) [@349iq2345](https://forum.onefinitycnc.com/u/349iq2345)
#### Post date: [May 2, 2022, 10:17pm UTC](https://forum.onefinitycnc.com/t/speed-control-dial-does-nothing-on-vfd-solved-vfd-wiring/12831/17 "2022-05-02T22:17:28Z")

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Hey Alex,

> [@Dr-Al](#):
>
> Then an EMI filter would be better.

the EMI filter on the input side of a VFD is to protect the house installation and other electrical devices connected to it from the EMI the VFD produces.

> ![Omron_MX2_Manual __General_Warnings_and_Cautions__ PXVII__Suppression_for_Noise_Interference_from_Inverter](https://us1.discourse-cdn.com/flex022/uploads/onefinitycnc/original/2X/0/095a61734100d077538d755c5cd87f92fd2e9492.png)  
> – Source: [Omron MX2 User’s Manual](https://assets.omron.eu/downloads/manual/en/v5/i570_mx2_users_manual_en.pdf)

What protects the VFD from power distribution system is the input-side AC reactor:  
 ![Omron_MX2_Manual __General_Warnings_and_Cautions__ PXVII__Effects_of_Power_Distribution_System_on_Inverter](https://us1.discourse-cdn.com/flex022/uploads/onefinitycnc/original/3X/3/5/35daeaa00f192cb5f0dc7926c86c5e12f345d4a9.png)

 ![Omron_MX2 __Basic_System_Description__ P028_pdf054](https://us1.discourse-cdn.com/flex022/uploads/onefinitycnc/original/3X/7/6/76f4dd5ee355b59ac300d7c934794d4fd9a63137.png)

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