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TW-357 REV E
24
Sensor Type
The sensor type can be set through the menu system (MENU, 2, 4). The sensor type selection should match
the sensor type that is being used in the system. This is a 4-sensor, a 7-sensor (Freeze-Guard) or an 8-sensor
array. If the sensor assembly is unplugged and the main control is still on, the display will indicate that a
sensor error has occurred. In addition the level indicated would be 8” on an 8-sensor assembly, 7” on a Freeze-
Guard assembly or “High Alarm” on a 4-sensor assembly. This occurs because the control cannot differentiate
between a very high resistance (when a thermistor is in LN2 ) and an infinite resistance (when an open circuit
appears in the level sensing circuitry).
Alarms and Error Conditions
The KRYOS control tracks many different conditions in the freezer and therefore, has a full complement of
alarms associated with these different conditions. As alarms occur, they cause an audible beep as well as a
flashing red light. A remote alarm relay is also triggered following a user-designated period of time, after the
error condition occurs, if it is not corrected. In addition, the error condition is displayed on the top line until
the error condition is corrected. When an error does occur, the audible alarm may be muted by pressing the
designated button. The audible alarm will then be silent until activated by a new error condition. The red light
will continue to flash until all errors are corrected. The remote alarm will be activated if the power is
interrupted.
The High Temperature Alarm for Thermocouple #1 can be set through the menu system (MENU, 3, 1). This
alarm is activated if the temperature rises above the designated temperature. The alarm temperature can range
from 0ºC to -190ºC. It can also be disabled.
The High Temperature Alarm for Thermocouple #2 can be set through the menu system (MENU, 3, 2). This
alarm is activated if the temperature rises above the designated temperature. The alarm temperature can range
from 0ºC to -190ºC and it can also be disabled.