Stray Capacitance

A couple of methods come to mind: the process of induction motors can be "silenced" by first filtering your power supply through a capacitor or a group of capacitors or batteries if you concentrate on isolating the ground side of your supply you may find the source of your "noise" more easily. Your correct in thinking you can over filter your supply this is why you experiment with a variable capacitor to identify your best solution and then fix that value in the finished process. remember the when you take your hands out of the equation copper shielding will resolve directional interference. everything is Radio frequency even artificial light sources.

Dear Queue;

Sorry for being late to reply to you.

The source of the noise we have is for sure from the high frequency switching on /off IGBTs of our VFDs, however, mitigation Harmonics with filtering the source will not solve the problem of the noise which it is EMC that simply can bypass these filters.

Our power system is IT ( Isolated neutral ) but still the noise pass through the stray capacitance of AC section of the system.

The recommended solution is re engineering the cabling, grounding, system and using an isolated power transformers.

I was asking about the calculation methods of these transformers.

The problem in using capacitors, is that during low loads situation the system will switch off unnecessary units leaving the system with less generators on line which then will suffer from over voltage by the reactive extra loads.

I would appreciate your comments.

M-Salem

Where on earth can I find a 3000A VFD too?