Power Supply and Control
Trace heat cables may be connected to single-phase or (in groups) to three-phase power supplies. Power is controlled either by a contactor or a solid-state controller. For self-regulating cable, the supply must furnish a large warm-up current if the system is switched on from a cold starting condition. The contactor or controller may include a thermostat if accurate temperature maintenance is required, or may just shut off a freeze-protection system in mild weather.
Electrical heat tracing systems may be required to have earth leakage (ground fault or RCD) devices for personnel and equipment protection. The system design must minimize leakage current to prevent nuisance tripping; this may limit the length of any individual heating circuit.
Read more about this topic: Trace Heating
Famous quotes containing the words power, supply and/or control:
“A state that denies its citizens their basic rights becomes a danger to its neighbors as well: internal arbitrary rule will be reflected in arbitrary external relations. The suppression of public opinion, the abolition of public competition for power and its public exercise opens the way for the state power to arm itself in any way it sees fit.... A state that does not hesitate to lie to its own people will not hesitate to lie to other states.”
—Václav Havel (b. 1936)
“Artistic inspiration ignores the law of supply and demand.”
—Mason Cooley (b. 1927)
“There has been something crude and heartless and unfeeling in our haste to succeed and be great. Our thought has been “Let every man look out for himself, let every generation look out for itself,” while we reared giant machinery which made it impossible that any but those who stood at the levers of control should have any chance to look out for themselves.”
—Woodrow Wilson (1856–1924)