IEC 61000-4-5 defines a typical lightning voltage waveform (Figure 3). The IEC 61000-4-5 standard also specifies test voltage levels for surge immunity in classes of electrical/electronic equipment (Figure 4). The levels are defined by the end application: ■ Class 1: Partially protected environment ■ Class 2: Electrical environment where cables are well-separated, even at short runs ■ Class 3: Electrical environment where power and signal cables run parallel
Figure 3: This is the lightning pulse waveform defined by IEC 61000-4-5 (IPP is peak current). (Image source: Eaton)
IEC 61000-4-5 SURGE TEST LEVELS
Maximum peak current at 2 Ω (A)
Class
Voltage leve (kV)
1
0.5
250
2
1
500
3
2
1,000
■ Class 4: Electrical environment having
4
4
2,000
interconnections run as outdoor cables along with power cables, and the cables are used for both electronic and electric circuits 3) IEC 61000-4-4 covers protection for EFTs (Figure 5). EFTs are caused by the operation of inductive loads, such as heavy-duty motors, relays, switching contactors in power distribution systems, and the switching in or out of power factor correction equipment.
X
Custom
Custom
Figure 4: IEC 61000-4-5 defines four classes of test levels for electrical surge immunity. (Image source: Eaton)
Figure 5: Shown is the EFT pulse waveform as characterized by IEC 61000- 4-4. (Image source: Eaton)
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