To protect the electrical equipment connected to the power distribution systems from the dangerous and detrimental conditions that can be created by transient voltages, the International Electrotechnical Commission (IEC) implemented the IEC 60204-1 standard as a means of categorizing devices by their ability to tolerate transients and setting conditional category requirements. This standard, titled "Safety of Machinery - Electrical Equipment of Machines - Part 1: General Requirements", identifies four categories of magnitude-based transient voltage tolerance at different operating voltages.
This chart outlines different working voltages and the tolerated transient voltage thresholds sorted by category. For example, if a device that operates at 300Vs is able to withstand 4000 transient volts, it would be considered a Category III device.
Transient Voltage tolerance at different operating voltages |
||||
---|---|---|---|---|
Working Voltage | Category I | Category II | Category III | Category IV |
150 | 800 | 1500 | 2500 | 4000 |
300 | 1500 | 2500 | 4000 | 6000 |
600 | 2500 | 4000 | 6000 | 8000 |
1000 | 4000 | 6000 | 8000 | 1200 |
Source Impedance | 30Ω | 12Ω | 2Ω | 2Ω |
Table 1: Transient Voltage tolerance at different operating voltages
This chart outlines different working voltages and the tolerated transient voltage thresholds sorted by category. For example, if a device that operates at 300Vs is able to withstand 4000 transient volts, it would be considered a Category III device.