•Using the same straight slot screwdriver, move the heater switch to dis-
play “230V”. See the rear panel drawing in Figure 1 on page 13.
NOTE:If the heater switch and the fuse holder do not both read 230V when
complete,the unit will either not heat or only heat at a fraction of its capacity.
Ifnot done properly, the unit could become damaged and void the calibration
and warranty.
CAUTION: DO NOT plug the unit into 230 V if the heater switch and fuse
holder read 115. This will cause the fuse to blow and may damage the in-
strument.
6.4 Setting the Temperature
Section 7.2 explains in detail howto set the temperature set-point on the cali-
brator using the front panel keys. The procedure is summarized here.
(1) Press “SET” twice to access the set-point value.
(2) Press “UP” or “DOWN” to change the set-point value.
(3) Press “SET” to program in the new set-point.
(4) Press “EXIT” to return to the temperature display.
When the set-point temperature is changed the controller will switchthe well
heater on or off to raise or lower the temperature. The cycleindicator, a two
color LED, will also indicate on (red and heating) or off(green and cooling).
The displayed well temperature will gradually change until it reaches the
set-point temperature. The well may require 5 to 20 minutes to reach the
set-point depending on the span. Another 5 to 10 minutesis required for the
temperature to stabilize.
6.5 Calibrating Probes
The dry-well block provides a constant temperature environmentin which
probes may be compared. The probes inserted into the block may be compared
to the well temperature displayed on the front panel of the calibrator.The
probes should be inserted the full depth of the well since the temperature at the
bottom of the well will most closely agree with the displayed temperature.
For greater accuracy the probes may be compared to a reference thermometer
inserted into the block. The reference thermometer may be inserted into one
hole while the probes to be calibrated are inserted into another. The drawback
to this method is that because of temperature variations throughout the block
there may be a small temperature difference between one hole and another
which can cause errors.
9140 Dry-well Calibrator
User’s Guide
18