Grid Phenomena

Voltage phenomena

Causes

Possible subsequent problems

Grid frequency

• Loss of power generators
• Big load changes

• Instability of the supply grid

Level of supply voltage

• Change in grid load

• Disturbance of equipment
• Plant shutdown
• Data loss

Flicker

• Frequent load changes
• Motor start

• Lighting flickering
• Impairment of the work performance of exposed persons

Dips / excesses of supply voltage

Rapid voltage changes (RVC) (often referred to as a transient)

• Big load changes
• Short circuits, earth connections
• Thunderstorms
• Overload of energy supply
• Feed-in of renewable energies, like by wind or photovoltaics

• Disturbance of equipment like controls or drives
• Breakdown
• Data loss of controls and computers

Voltage interruptions

• Short circuits
• Triggered fuses
• Component breakdown
• Planned interruption of supply

• Loss of production
• Process interruptions
• Data loss of controls and computers

Imbalance of supply voltage

• Uneven load of phases due to single or two-phase consumers

• Current in the neutral conductor
• Overload / overheating of equipment
• Increase of harmonics

Harmonic voltages

• Non-linear loads like frequency converters, rectifiers, switching power supplies, arc furnaces, computers, fluorescent tubes, etc.

• Reduction of machine efficiency
• Increased energy losses
• Overload / overheating of equipment
• Current in the neutral conductor

Interharmonic voltages, voltages for signal transmission

• Frequency converters and similar control devices

• Flicker
• Disturbance of ripple control

Transients

Fast changes in a wave form low frequency/high frequency

• Lightning strike
• Switching operations

• Destruction of equipment
• Data loss
• Plant shutdown