The Frost Heave Prevention control system is designed to minimize the energy used to prevent frost heave and to minimize the heat transferred through the floor that must be re-cooled by the freezer cooling unit.
Temperature Sensors - To provide temperature feedback on the control and operation of the system, up to eight temperature sensors (RTD elements) can be located in conduit positioned between the heating cable conduit. The sensor leads are wired to a control panel selector switch.
Control Panel -
The control panel is a single enclosure that includes
the following:
a. 3-phase load center w/ branch circuit
breakers (208 or 277 VAC)
b. Branch circuit ground fault
protection
Ground fault circuit breaker (208 VAC) or Ground fault
switch (277 VAC)
c. Branch circuit solid state relays
(zero voltage crossover) to modulate or control the
amount of electrical power to the heating cable sets.
These relays are controlled by the temperature controller
and "fine-tune" the
exact power required to maintain the desired subfloor
temperature.
d. Temperature of each sensor can be checked using selector switch. System operation is also selected using this this switch (control sensor is typically located in the center of the freezer floor).
e. Auto-On-Off Switch - The
Control Switch allows for:
Auto-Mode - normal automatic control
On-Mode - testing
and control system repair
Off-Mode - freezer operations
off
f. Branch Circuit Alarm Light - provides
an easy-to-identify light that indicates that one
or more of the branch circuits has lost power (circuit
breaker trip, etc).
