LE-80 Laird Technologies, LE-80 Datasheet - Page 19

• Manufacturer Part Number: LE-80
• Description: THERMOELECT MOD SERIAL TRANSISTR
• Manufacturer: Laird Technologies

Specifications of LE-80

• Accessory Type: Temperature Control
• For Use With/related Products: AA Assemblies
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Voltage
As the thermoelectric principle requires DC
voltage, our TE assemblies are intended for
DC operation only. All standard assemblies
are designed for either 12 or 24 V DC opera-
tion. However, we also supply 48 V DC ver-
sions of larger assemblies and 5 V versions
of the smallest assemblies.
Input voltage for the standard fans has to
be within ±10% of nominal voltage and with
max. 5% ripple for optimum functionality
and service life. Do NOT use switched PWM
voltage for the fans.
Input voltage for the TEMs can be reversed
for heating, regulated down to 0 V DC and
up to ±110% of nominal voltage. For swit-
ched PWM voltage, use a PWM frequency
above 5 kHz to prevent service life reduction
due to thermal cycling effects on the TE
modules.
Guidelines for installing your TE assembly
General:
• Minimize thermal losses and condensation
by insulating all possible cold surfaces in
your system (DA, DL, LA, LL).
• Secure good ventilation on the warm side
(AA, DA, LA). Separate the inlet air from
outlet air, if necessary by using air-ducts and
hosing (see page 17). If the warm side is
built-in, make sure the inlet air comes from
the outside.
• Be sure to use an external fuse with a
rating of at least 150% of nominal current.
AA assemblies
• For non-insulated (electronic) cabinets,
the warm air on the warm side must not
heat up the cabinet, while cold air on the
cold side should not blow directly onto the
cabinet.
• Check that the enclosure is sealed and
that there is a tight fit between assembly and
cabinet.
Fans
The fan is the only moving part in a thermoe-
lectric assembly (Air systems). Consequently,
V O LTA G E
FA N S
there’s an obvious correlation between the
service life of the fan and the service life of
the assembly. All standard fans are brush-
less with ball bearings.
Expected service life at 25°C is 50,000
hours (L10). We also provide fans with IP55
moisture protection, high performance fans
with a service life of 100,000 hours (L10) or
other fans suitable for your application. For
more information, see page 17 or contact
Supercool.
Temperature control
Supercool offers a broad range of controllers
for a variety of applications.
Below are some aspects to consider when
selecting a controller for your application:
• Required temperature accuracy and hys-
teresis
• Temperature range of your application
• Max. current requirements
• Is your application only for cooling or
cooling/heating (reversible)
• Requirements regarding system efficiency
(COP)
• For insulated cabinets, make sure you
have sufficient insulation and that there are
no cold bridges.
• In a condensing environment, be sure
to mount the cold side heat sink fins in a
vertical position in order to drain the con-
densation.
DA/DL assemblies
• The cooled object is attached to the cold
plate with 4-9 screws. Apply a thin layer
of thermal conductive compound between
surfaces.
• To ensure optimum performance, the
flatness of the cooled object should be 0.05
mm/100 mm.
• When cooling a container or tank, use 3-
5 mm of Al sheet (or equivalent) to ensure
good thermal transfer. If you use a stainless
steel tank, remember to mount an Al sheet
with a larger surface area than the cold plate
to improve thermal transfer.
T E C H N I CA L IN FO R M ATI O N
TEMPERATURE CONTROLLERS
19
• Need for programming communication
(RS232) or display of set values
• Need for alarm signal outputs, low voltage
protection etc.
Please see page 14-15 for a description of
available controllers.
In order to maximize the reliability and ser-
vice life of your TE system, bear in mind the
following:
• When regulating in ON/OFF mode make
sure cycle time is 60 sec. or more
• If you use your own PWM-controller make
sure the switching frequency is 5 kHz or
more
• Do NOT use switched PWM voltage for the
fans. Use separate true DC power input for
fans.
• In critical applications, we recommend our
EC-26 or PR-59 (see page 14-15) to mini-
mize thermal stress.
LA/LL assemblies
• For superior performance even at lower
liquid flow rates, or when a gas is cooled,
turbulators are inserted into the liquid chan-
nels. Should your application call for a lower
pressure drop, the turbulators can be remo-
ved.
• Recommended liquid flow on the warm
side is 2 lit/min or more. Lower liquid flow
rates lead to a slight reduction in cooling
power.
• Recommended liquids are water with gly-
col or Fluorinert (3M).
• Remember to use a pump with the lowest
thermal leakage and heat generation.
• Be sure to insulate the liquid heat sink and
tubing to reduce thermal leakage.