Overview
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and OFF when the reading goes above the setpoint. Since the coil is nor-
mally ON with low readings, if power is lost accidentally, the coil turns
OFF which, in turn, reverses the relay contacts as if a high ppm reading
oc-curred; hence fail-safe.
The following chart lists all combinations of contacts, modes, and alarm
conditions.
Condition NO Contacts NC Contacts
(pins 5, 6) (pins 4, 5)
Low Power Mode Open Closed
Moisture Below Alarm Setpoint
Low Power Mode Closed Open
Moisture above Alarm Setpoint
Fail-safe Mode Closed Open
Moisture below Alarm Setpoint
Fail-safe Mode Open Closed
Moisture above Alarm Setpoint
Loss of Power Open Closed
Special Functions
Cell Test (Display Cell Voltage Level)
The cell test function verifies that the cell power supply is operating
properly. The voltage level of the 50VDC, 70-mA cell power supply is dis-
played. If a cell is very wet, the current needed to dry exceeds the power
supply capacity and the voltage reading will drop. With 70 mA continu-
ous-ly drying the cell, power supply voltage will increase over time and
the cell eventually will start to operate correctly. This voltage decrease
protects the power supply from too-high load conditions. Readings taken
in this condition should not be considered accurate.
Electrical Test (Display Logic Voltage Level)
The electrical test function verifies that the 5VDC power supply is operat-
ing correctly. This voltage powers the microprocessor and related logic in-
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