Electrical HeatingTransfer of Heat

Heat is transferred from a hotter region to a colder region

Electrical HeatingHeat is Energy

Energy in Joules (J) Power in Watts (W)

Time in seconds (s)

Electrical HeatingTemperature Scales

To convert Kelvin to Celsius:

Electrical Heating

Specific Heat CapacitySpecific Heat Capacity is the amount of heat energy required to change the temperature of one kilogram of a material through ONE KELVIN (or degree C)

Absolute Heat Energy (J)

Mass (kg)

Temperature change (K or oC)

Specific Heat Capacity(J/kg.K)

Electrical Heating

Heat Control – 3-Heat Switch

Electrical Heating

Heat Control – 3-Heat Switch

Electrical Heating

Heat Control – Open/Closed Cycle

Electrical Heating

Heat Control – Thermostats

Bi-Metal Thermostat

Support Stem

Mounting Flange & Screw Thread

Helical Bi-Metal Strip

Brazed to Rod

Invar RodBrazed to Stem

Electrical Heating

Heat Control – Thermostats

Expanding Tube Thermostat

Brass Tube

Invar Rod

Tube Brazedto Rod

Tube Brazedto Support

Retaining Clips

Tube Expands/Contracts

Rod Free End Moves to operate contacts

Electrical Heating

Heat Control – Thermostats

Capillary Tube Thermostat

Bellows Rod moves to operate contacts

Bulb with volatile liquid

Capillary TubeBellows or Diaphragm

Electrical Heating

Heat Control – Thermostats

Bimetal Disc Thermostat

This thermostat has contacts operated by a cupped bimetal disc.

At a pre-set temperature, the disc snaps the contacts open.

When the disc cools to a preset value, disc returns and the contacts snap closed.

Electrical Heating

Heat Control – SimmerstatThe SIMMERSTAT is an OPEN CYCLE temperature control commonly used with stoves.

Heating Load

Active

Neutral

Contacts

Internal heater element

Operating Bimetal

Compensating Bimetal

Pivot