Fluke 7312, User Manual

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9.8 Cutout
As a protection against software or hardware fault, shorted heater triac, or user
error, the bath is equipped with an adjustable heater cutout device that shuts off
power to the heater if the bath temperature exceeds a set value. This protects
the heater and bath materials from excessive temperatures and, most impor-
tantly, protects the bath fluids from being heated beyond the safe operating
temperature preventing hazardous vaporization, breakdown, or ignition of the
liquid. The cutout temperature is programmable by the operator from the front
panel of the controller. It must always be set below the upper temperature limit
of the fluid and no more than 10 degrees above the upper temperature limit of
the bath.
If the cutout is activated because of excessive bath temperature, the power to
the heater is shut off and the bath cools. The bath cools until it reaches a few
degrees below the cutout set-point temperature. At this point, the action of the
cutout is determined by the setting of the cutout mode parameter.
The cutout has two selectable modes – automatic reset or manual reset. If the
mode is set to automatic, the cutout automatically resets when the bath temper-
ature falls below the reset temperature allowing the bath to heat up again. If the
mode is set to manual, the heater remains disabled until the user manually re-
sets the cutout.
The cutout set-point may be accessed within the secondary menu. Press the
“SET” and “EXIT” button to enter the secondary menu and show the heater
power. Then press the “SET” button twice to access the cutout set-point.
S+E
Access heater power in secondary menu
12 Pct
Heater power in percent
S
Access proportional band
Pb = 0.101C Proportional band setting
S
Access cutout set-point
CO = 110C Cutout set-point
To change the cutout set-point, press the “UP” or “DOWN” button.
D
Decrement display
CO = 75C New cutout set-point
To accept the new cutout set-point, press the “SET” button.
49
9 Controller Operation
Cutout