Neutral Earthing

Neutral Earthing Resistors (also known as neutral grounding resistors in US influenced regions) are a key component in earth fault protection of medium voltage electricity generation and distribution systems.

Cressall NERs limit the current that would flow through the neutral point of a transformer or generator in the event of an earth fault.

Features of Cressall earthing resistors include:

• Any current or voltage rating
• Compliance with either IEC 60076-25:2023 “Power Transformers , Neutral Grounding Resistors”  or IEEE-C57-32a (2020) “Standard for Requirements, Terminology, and Test Procedures for Neutral Grounding Devices” (formerly IEEE-32).
• Stainless steel resistors and enclosures as standard, IP23 to IP56.
• Type-tested standard designs (certificates available)

Options include:

• Supply of resistor banks only for incorporation into customer’s own enclosures
• Shock-tested marine designs
• Provision for CTs, heaters, special cabling, etc.
• Interlocked off-load by-pass isolators
• Single or multiple vacuum contactors
• High resistance grounding resistors (for use where regulations permit, e.g. some offshore installations)