Enclosed Power Electronics

DOE-HDBK-1092-98

9.12 ENCLOSED POWER ELECTRONICS

Power electronics equipment is equipment that uses electronic components and subsystems to

control significant amounts of electrical energy. Examples of power electronics systems include:

Accelerators, magnets, x-ray systems, and other research equipment;

Radio and radar transmitters;

Variable speed motor drives; and

All applicable portions of this section should be addressed due to the hazards involved with this type

of equipment.

9.12.1 ENCLOSURES

Power electronics equipment should be constructed in all-metal enclosures for containment of fire,

high energy, and electromagnetic radiation hazards.

The enclosures should support the housed equipment, provide strength to brace conductors against

short circuit forces, and protect housed equipment against physical damage.

It is usually easier to provide barriers to protect the electronics enclosure from collision and missile

hazards rather than strengthening the enclosure itself.

9.12.2 COMPONENT CLEARANCES

Enclosures must provide adequate clearance from energized parts. The required clearances depend

on the shape of the conductor, the surface characteristics of the conductor and enclosure, the voltage

characteristics, environmental conditions, and creepage. The breakdown strength along the surface

of supporting insulators may require larger clearances than breakdown in air.

All power electronics enclosures shall provide adequate room for access to parts and subsystems for

expected maintenance and modification. Consideration should be given to handling provisions for

heavy parts and subsystems, access to test points and calibration adjustments, and work clearances

for safe access to enclosure interiors.

Safe work on high-voltage equipment requires installation of manual grounding devices on exposed

high-voltage conductors. Enclosure size shall provide adequate room to safely apply and remove

grounding devices, and permit grounding devices to remain in place without interfering with

expected work.

Enclosures shall be sized to allow cables to be installed and routed without infringing on required

clearances from high-voltage conductors.

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