What is the voltage tolerance curve?

In the 1980s, the United States Computer and Business Equipment Manufacturers Association (CBEMA) requested power quality for large-scale computers, and proposed voltage tolerances and related four typical voltage disturbances to prevent voltage disturbances from causing the computer and its control devices. Misoperation and damage. The four voltage disturbances are voltage drop, voltage rise, spike and power failure. The voltage tolerance limit has been adopted by the IEEE and has become the US power quality standard. CBEMA voltage tolerance curve.

The basic concept of the CBEMA voltage tolerance curve is that the voltage in the shaded part of the envelope is a qualified voltage, and the voltage outside the envelope is a defective voltage. The voltage below the envelope will de-energize the load, and the envelope The above voltage will cause insulation problems, over-voltage tripping or over-excitation of other equipment.