Chapter hvac engineering Fundamentals: Part 1 Introduction

404
Chapter Twelve
Figure 12.2
Typical form that supplies information on motor control features to the elec-
trical designer.
Electrical Features of HVAC Systems
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Electrical Features of HVAC Systems
405
detection systems go into alarm, the fan systems must turn off. Fur-
ther sophistication gets into smoke control in buildings, a separate
topic by itself.
Lighting systems:
The HVAC designer must fully understand the
building lighting systems to be able to correctly respond to the cool-
ing loads which develop. Any inordinately high lighting loads may
stimulate discussion and evaluation of lighting fixture selection. Au-
tomated lighting control may be included as a feature of a building
automation system.
Transformer vaults:
Electric transformers typically lose 2 to 5 per-
cent of the power load (winding losses) to the ambient air. Building
transformers may wind up in underground vaults, in secure rooms,
in janitor closets, or in ceiling spaces. Dissipation of the heat with
ventilation is often a challenge. Note that even though the load may
decrease, transformers seldom sleep; 24 h / day ventilation is re-
quired. Building HVAC systems which follow a time-clock schedule
are inadequate for transformer rooms. Some electronic monitoring
and control devices cannot tolerate ambient air temperatures above
about 100
⬚
F.