Electro Magnetic Interference (EMI)
- RFI Radio Frequency Interference
- Common Mode Noise
Unwanted high frequency electrical noise can cause equipment to malfunction. EMI (Electro Magnetic Interference) and RFI (Radio Frequency Interference) are two types of electrical noise.
Causes of High Frequency Noise
These frequencies can be from either noise conducted through power lines or radiated through the air onto the power lines. Variable Frequency Drives are one of many types of equipment that can generate EMI. In the case of VFDs, the electrical noise produced is primarily contained in the switching edges of the PWM controller. These switching frequencies also increase the amount of electrical noise.
Indicators of Equipment Interference
- Dimmer and ballast instability
- Lighting disturbances such as flashing
- Poor radio reception
- Poor television reception
- Instability of control systems
- Flow meter totalizing
- Flow metering fluctuation
- Computer system failures including the loss of data
- Thermostat control problems
- Radar disruption
- Sonar disruption
High Frequency Noise Solutions
KRF filters use a combination of high frequency inductors and capacitors to reduce noise in the critical 150kHz to 30MHz frequency range.