In the '3.1.2 Test Method for Power Ports (Common Mode)' section of the 'Square-Wave Impulse Noise Test Method Guidebook,' it states: 'For AC power supplies, positive and negative polarity impulse noise is applied to L, N, and PE against the reference gro

In the '3.1.2 Test Method for Power Ports (Common Mode)' section of the 'Square-Wave Impulse Noise Test Method Guidebook,' it states: 'For AC power supplies, positive and negative polarity impulse noise is applied to L, N, and PE against the reference gro

The standard is the grounding-line standard.
The JEM-TR177 standard referenced by our guidebook contains the following statement.
“6.2.3 Grounding-line noise test
This normally corresponds to the common-mode test on protective grounding in a power-supply noise test."

The protective grounding above refers to the protective grounding within the power line, meaning PE.