Fluke 7381 User Manual page 43

The HGb ( HGb ) modes are:
• Auto (normally-set mode)
• On (manual)
• Off
If for a special application, the automatic mode is undesirable, set the HGb to On or Off.
Automatic Mode: This mode is best for most applications. When you scan down in temperature
(for set points >2 °C below the current temperature) the system switches to maximum cooling
capacity. The system automatically switches back to HGb mode just before it reaches the new
set-point, but only if the new set-point is >-61 °C. When in this mode, the HGb setting adjusts
automatically to ensure the percent of heater power is approximately 30 %. For temperatures
<-61 °C, the capacity remains in the maximum-cooling condition. Maximum cooling is generally
required at these low temperatures.
On Mode: This mode allows for the manual selection of thehot gas capacity control setting for all
temperatures and conditions where the refrigeration is on. The HGb capacity control setting has
a range of 40 to 448 (with 40 being the setting with no capacity reduction, and 448 being the
setting with maximum capacity reduction). An increase of the HGb setting decreases the cooling
power and, correspondingly, reduces the percent of heater power applied to maintain the
temperature.
Off Mode: This mode does not permit capacity reduction and the cooling is at maximum
throughout the temperature range used by the refrigeration.
The cooling capacity of the system can exceed the capacity of the heater at higher
temperatures.
To change the HGb parameter:
1. Push SET to access the parameter setting.
Auto
2. Push DOWN to select
3. Push SET to store the change or push EXIT to ignore any changes made and escape to the
menu.
After you set the mode selection, the display shows the HGb setting (
Off mode. The temperature controller automatically selects the HGb setting for Auto mode and
this cannot be manually adjusted. The user must select the HGB setting in On mode.
HGb mode is set for automatic operation
On or OFF modes.
Note
Calibration Bath
Controller Operation
) unless the HGb is set to
St
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