COMMERCIAL THERMOSTATS

DEFINITION OF TERMS
• Automatic Reset: A type of thermostat that will automatically reset at a specific temperature (i.e. a thermostat operates at
65,5 oC [150 oF] and resets at 48,89 oC [120 oF]).
• Bimetal: Two dissimilar metals bonded together to form the material for manufacturing thermally-sensitive discs which actuate
the thermostat.
• Close on Rise (COR): Refers to operation of the contacts. When the temperature rises to its set point, the contacts close or
make contact and complete the circuit.
• Contact Resistance: The value of resistance measured between the terminals.
• Dielectric Strength: The value of insulation between two electrically conducting parts. It may be tested by the application of a
predetermined overvoltage for a specified time.
• Differential: The temperature difference between the operate and reset set points, also known as operate and reset.
- Nominal: The temperature difference between nominal set points regardless of tolerance.
- Maximum: Maximum number of degrees between actual opening and closing set points.
- Minimum: Minimum number of degrees between actual opening and closing set points.
• Exposure Temperature: Thermal environment of a device during application operation.
• FLA (Full Load Amps): Current taken from the line by the motor when the motor is yielding the rated hp at the rated voltage
and frequency.
• Life Cycles: The endurance rating of the thermostat expressed in number of operations with stated electrical load applied.
Temperature limit application = open on rise.
• LRA (Locked Rotor Amps): The amount of current the motor can be expected to draw under starting conditions when full
voltage is applied, also known as starting inrush current.
• Manual Reset: A bimetal thermostat with a reset button that must be pressed to reset the contacts.
• Open on Rise (OOR): Refers to the operation of contacts. When the temperature rises to its set point the contacts open,
terminating the circuit.
• Overmold: Encapsulation with an insulating material.
• Phenolic: Thermoset plastic used for the insulating body of the thermostat.
• Set Point: The nominal temperature at which the thermostat operates.
• SPST (Single Pole/Single Throw): A switch with one current path which can be either open or closed.
• Tolerance: The allowable range above and below the set point temperature.
• Operate: Change of state when the thermostat reaches its set point.
• Reset: Change of state when the thermostat returns to its original condition prior to operation.
NOTES
• Standard Temperature Characteristics Tables:
- Temperatures: Please consult applications engineering for temperature ranges, tolerances and differentials not noted.
The operating temperature ranges include tolerances.
- Tolerances: The ± tolerances given have been established after review of many thermostat applications. Attempts should
be made to establish the widest acceptable tolerance possible.
• UL and CSA Approvals: 12,7 mm [0.5 in] thermostats are available with multiple agency approval for incorporation into
equipment.
• Fan control applications: Require thermostat set points to be derated by 20 °C from the equivalent temperature limit
application. They also close on rise.
• Dimensions: Are for reference only and are given in mm [in].