Wiegmann WPG Series User Manual

Page 2

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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.

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