Lakeshore 335, Руководство пользователя, Страница: 50 / 172

38 c
HAPTER
3: Installation
Model 335 Temperature Controller
3.7.5.2 Power Supply Setup
Follow all operation and safety instruction in the power supply manual during setup.
Please consider the following suggestions for protecting the power supply and
heater load.
D
Short circuits are common in cryogenic lead wiring. If the power supply does not
specify that it is short circuit protected, the power output should be wired with a
fuse in series to prevent damage.
D
Unipolar power supplies are designed to use a positive programming voltage and
some can be damaged if the programming voltage is negative. Be careful when
wiring the system to maintain the correct polarity. Never set the control output
of the Model 335 to bipolar mode when using a unipolar power supply.
D
Some power supplies can be damaged if there is a programming voltage present
at their input when they are turned off. This can happen if the Model 335 and
power supply use a different source of line power or are turned on and off individ-
ually. It can be avoided if the two instruments share a switched power strip.
D
The heater and wiring in the system must be rated for both the maximum current
and maximum voltage provided by the power supply. The Model 335 can be set
to warm up using less than full power if the load will not tolerate the full power of
the supply.
3.7.5.3 Connecting to the Model 335
The voltage programming cable attaches to the removable terminal block on the rear
panel of the Model 335 (FIGURE 3-9). Output number and polarity of the output
leads are labelled. The negative (–) terminals are connected internally to the instru-
ment chassis to provide a ground reference.
In the most basic configuration, a two-conductor cable connects directly from the
output terminals to the power supply programming input. Copper wire size 20 AWG
to 26 AWG is recommended.
FIGURE 3-9 Output terminal block