5
Series GEN 2 Ultrasonic Humidifier IOM Manual
outlet. The drain valve solenoid is controlled by the Level Controller to drain water from the tank via the
drain outlet. If the water level in the tank exceeds the height of the overflow pipe, the excess water is
diverted to the drain outlet. The drain outlet pipe is 1/8” MPT and ships with a stainless steel cap.
Temperature Sensor
The temperature sensor monitors the temperature of the tank and is read by the Level Controller which
prevents overheating and freeze protection
Solid State Relay
The 48VDC operating voltage for the Ultrasonic Nebulizer Units is switched on and off by a solid state DC
relay controlled by the Level Controller.
Level Controller
The Level Controller is a microprocessor based device located in the electric box that receives inputs
from sensors and other inputs and in turn controls the valves, fan and Ultrasonic Nebulizer units. It
consists of a DC-DC power supply to convert the 48VDC to 24VDC for the fans and solenoids and a
further reduction to 5VDC for the microprocessor, sensors, power switches and either a Modbus interface
to communicate with the Ultra-Series Control box or a simple standalone input interface depending on
which model humidifier was purchased.
The 48VDC must be present at all times to allow the Level Controller microprocessor to monitor the inputs
and control the outputs.
The microprocessor monitors the On and Off command from either the Modbus or the input dry contact
(depending on which model was purchased). If commanded on, the microprocessor checks the Low
Water Float Switch and the High Water Float Switch. If the water is too low, the microprocessor turns on
the Water Fill Valve Solenoid and monitors the Float Switches.
When the water level is above the low water level, the fan is turned on. When the water level is above the
high water level, the Water Fill Valve Solenoid is turned off and the Solid State Relay is turned on. When
the water level falls below the high water level, the microprocessor turns the Water Fill Valve Solenoid on
again to maintain optimal water level. When the on/off command is removed, the Solid State Relay is
turned off and, after a few seconds time delay to eliminate the remaining mist out of the humidifier, the
Fan is turned off.
Proportional control is accomplished by the microprocessor monitoring the proportional signal from the
Modbus or proportional input (depending on which model was purchased). When the proportional signal
is greater than 10% of the maximum input, the microprocessor will turn the Solid State Relay on and off in
a pulse-width modulation control. The period of the pulse width is 1 seconds.
For 10% control, the Solid State Relay is turned on for 0.1 seconds and off for 0.9 seconds. The on time
increases as the input approaches 100%. At 100%, the Solid State Relay is on continuously.
Safety control is built into the microprocessor. The voltage applied to the transducer controls the amount
of mist produced. Too high a voltage can cause damage to the transducer and too low a voltage prevents
mist from being formed. The microprocessor monitors the 48VDC to be with a range of voltages. If the
voltage is out of range, the microprocessor will not energize the Solid State Relay.
If the temperature of the tank rises too high, the microprocessor will turn off the Solid State Relay. If the
temperature approaches freezing, the microprocessor will turn off the Solid State Relay and the fan, and
then drain the tank to prevent damage from freezing water. When the temperature returns to a safe level,
normal operation is resumed.
A low level alarm is annunciated when the microprocessor sees the Low Level Float Switch indicate low
water after the tank has been filled. A fill alarm is annunciated when the High Water Float Switch does
not indicate the water level has been achieved after a predetermined amount of time.
A transducer alarm is annunciated if the transducers have been energized and no water is used in a
predetermined time (indicating no transducer is functioning). For the Modbus version of the Level
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