3M KSR-2, Инструкция по применению

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To use the 3M Heat Trace Bill of Materials Tool, visit 3M.ca/HeatTrace
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Step 5: Establish control method needed to operate the system.
Energizing the Heating Cable
All snow melting systems should be controlled to turn the heating cable on and off as conditions warrant. There are
three basic means to activate a snow melting system:
A. Manual
• On/off switch — simple to install and economical to purchase; requires diligence on the part of
the operator.
B. Automatic
• Ambient sensing control — turns system on and off based on ambient temperature. Heating cable will
frequently be energized during non required times.
• Automatic control — turns system on when precipitation is detected and temperatures are in the range
where snow or freezing rain is likely.
Some applications, such as truck scales and loading zones, are subject to freezing water or slush accumulation even
though no precipitation is falling. To properly deal with these conditions, a custom-designed control system is typically
required and the designer should contact 3M for assistance at 3Menergysolutions@mmm.com .
Example:
Because the facility will be occupied during normal business hours, the system is to be controlled
automatically. To accomplish this, an STC-DS-2C snow and ice sensor will be utilized.
A power distribution and contactor panel would consist of a main three-pole breaker, a three-pole contactor and three
40 amp branch circuit breakers equipped with 30 mA ground-fault protection. The panel would also be equipped with a
hands-off/auto switch plus lights to indicate system status.
Because the panel will be located indoors, a NEMA 12 enclosure is suitable for the panel. If the panel was to be installed
outside, a NEMA 4 or 4X enclosure would be required.
Providing power distribution and contactors: When a snow melting system requires four or more heat tracing circuits,
it is recommended that a dedicated power distribution and contactor panel be utilized. By keeping the snow melting
circuit breakers in a dedicated panel, several design and operation advantages will occur:
Figure 3.4.5
Power/End Terminations
Ckt. #1
9" O.C. Type
Ckt. #2
Ckt. #3
Expansion
Joint Kit Type
Expansion
Joint Kit Type
Figure 3.4.4
Building Entry
Phone/Cable
Room
Possible Power/End
Termination Locations