Induction and Dielectric Heating Equipment

DOE-HDBK-1092-98

1. Select cables that are listed by an NRTL for a given type of installation (such as in conduits,

trays, underground, or in an enclosure) whenever possible. Since cables used for R&D are

sometimes unique (such as some coaxial cables), they may not be available as NRTL listed.

In that case, obtain AHJ approval.

2. Where liquid- or gas-cooled conductors are used, sensing devices (temperature or coolant-

flow) shall be provided for alarm purposes or equipment shutdown if the cooling system

malfunctions. Provide adequate labeling, insulation, or other protection for metallic cooling-

water piping used as electrical conductors.

3. Provide engineering calculations to support overrating of conductors for any application.

Avoid conductor loops (wide spacing) between high-current supply and return conductors to

prevent voltage and current induction in adjacent circuits or structural members.

4. Ground coaxial cable shielding when possible. If test conditions require an ungrounded

shield, provide barriers and warning signs to notify personnel that the shield is ungrounded

and should be assumed to be energized. Provide suitable routing and additional protection for

coaxial cables used in pulsed-power applications where the braid of the coaxial cable rises to

high voltage levels.

10.10.3.3 OPERATION AND MAINTENANCE

Cable connectors and connections should be checked after installation, periodically, and should be

tightened as necessary. Special attention should be given to aluminum cable connections.

Ensure that charges are not built up on equipment that has been disconnected, such as vacuum

feedthrough systems.

10.10.4 INDUCTION AND DIELECTRIC HEATING EQUIPMENT

This section describes electrical hazards associated with induction heating, RF equipment, and

microwave equipment used in research. The hazards are mainly associated with high-power/high-

frequency RF generators, waveguides and conductors, and the working coils producing high

temperatures.

10.10.4.1 HAZARDS

1. RF power as high as 50 kW and frequency in the tens of kHz range to hundreds of MHz is

supplied from the RF and microwave generators. Being close to or making contact with an

unprotected coil, conductors or waveguide opening may result in severe body burns.

2. Dangerous voltages are present inside the power generators.

3. Dangerous levels of RF energy may be present in the laboratory.

10.10.4.2 DESIGN AND CONSTRUCTION

1. The heating coils, sources of high-frequency energy, and other live parts outside the generator

cabinet must be shielded or guarded to prevent access or contact.

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