Wiegmann WPG Series - Manual (Page 2)

K2
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Data Subject To Change Without Notice
E N V I R O N M E N TA L C O N T R O L S
G E N E R A L I N F O R M AT I O N
Wiegmann has always recognized
that our customers in the electrical
and electronic marketplace need reli-
able, high quality enclosures and
environmental control products to
meet their protection requirements.
Protection Requirements today not
only mandate NEMA TYPE 12, 3R, 4,
& 4X, but also require a broad mix of
BTU & size selections. Wiegmann is
proud to offer those choices via a
whole new line of A/C products. They
are: Advantage Series, Trim Line
Series, Micro-Mini Series, Integrity
Series, and the Top Mount Series.
Three Basic Cooling Methods
When selecting a cooling method
there are three types to consider.
1 Passive Ventilation — If there is
only a minimal heat gain in your
circumstance, use of louvers or
grilles with filters can be effective.
This method, however, usually pro-
vides less cooling effect than is
necessary with today’s components.
2 Forced Convection Air Cooling —
If the installation will be in a clean,
non-hazardous environment with
an acceptable ambient (outside the
enclosure) temperature range, a
simple forced-air cooling system
utilizing outside air is usually ade-
quate. Combined with an air filter,
such devices generally meet the
heat removal needs of typical elec-
tronic equipment and many electri-
cal applications (Fig. 1). Examples
of forced convection air cooling are
filtered fans, fan trays, and blowers
of various types.
3 Closed-Loop Cooling — In harsh
environments involving high temper-
atures, wash-down requirements,
heavy particulate matter or the
presence of chemicals capable of
damaging components (NEMA 4 or
12 environments), ambient air must
be kept out of the enclosure. Closed-
loop cooling consists of two sepa-
rate circulation systems. One sys-
tem, sealed against the ambient air,
cools and recirculates the clean
cool air throughout the enclosure.
The second system uses ambient air
or water to remove and discharge
the heat. Examples of closed-loop
cooling equipment employed with
electronics and process controls
are heat exchangers and air
conditioners.
FIGURE 1 — Forced Convection Method
FIGURE 2 - Closed Loop Cooling Method
Fans and Blowers can be used to pressurize (preferred) or exhaust cabinet air.
The ambient air should be filtered before it enters the cabinet.
Pressurized System — pushes air through enclosure
In an air-to-air heat exchanger, heat from air surrounding the
electronics is removed by a specially designed heat transfer
element before being routed back into the enclosure.
Filter & Grille
Required
Ambient Air
with Heat
Load
Ambient
Air
Fan or
Blower with
filter & grille
Cabinet
Fan or Blower
with filter &
grille
Cabinet Ambient Air
Ambient
Air with
Heat Load
Filter & Grille
Required
Blower
Ambient Air
with Heat
Load
Heat Exchanger
Ambient Air
Blower
Cooled Air
Heated
Air
Exhaust System — pulls air through enclosure
Ambient Air
with Heat
Load
Ambient Air
Heated
Air
Condenser
Blowers
Evaporator
Chilled
Air
In air conditioners, a condenser, an evaporator, and two blow-
ers combine to chill the air circulating in the enclosure.