4.The modulation signal must increase from minimum toward maximum as sensed RH (actual RH) drops below desired RH (%RH setpoint). In response, humidifier’s steam output will increase from minimum toward maximum. When humidifier’s steam output (lbs/hr) matches humidification load (lbs/hr), modulation signal will stabilize.
5.
Always refer to the external control’s wiring diagram factory supplied with each Liebert modulation control option.
6.Varying dc Voltage Modulation Signal Powered by Others: SGH humidifier can be factory configured to accept the following vdc signals:
7.Varying dc milliAmp (mA) Modulation Signal Powered by Others: SGH humidifier can be
OPTIONAL MODULATION (CONTINUOUS CONTROL) PACKAGES BY LIEBERT
Modulation (continuous control) “packages” are offered as accessories by Liebert.
OPERATION
INTRODUCTION
When the humidifier is first turned on, the controller starts with a self test procedure, which takes about 10 seconds. The test consists of activating for a short time the drain valve, fill valve, and power relays. The sound of the working solenoids is an indication of valves operation. Green and yellow lights flash during this time.
If there is no call for humidity, the humidifier is standing by and green light flashes. When control loop is closed ( Figure #13), the green light is steady on
and the humidifier starts its operation. The controller waits 10 seconds before energizing the
During operation, the controller measures the rate at which water is converted to steam and thus the mineral content of water inside the cylinder. When this rate exceeds the design optimum, a drain of the cylinder takes place. The amount of water drained is just enough to keep the contained water at design levels.
During start up, when mineral content in the water is low, water will reach the top of the cylinder at which point the yellow indicator light will come on. This is normal operation with a fresh cylinder. After a period of time the water level will drop and the yellow light will turn off.
High water level in the cylinder also indicates that the cylinder is near the end of its service life as electrodes become coated with minerals. The yellow light coming on more often would be the first indication of approaching the end of the cylinder life.
SGH OPERATION
END OF CYLINDER LIFE
When the cylinder is used up and water level can no longer stabilize below full cylinder (due to fully coated electrodes), the yellow light will flash in 4 pulse cycles. At this time the control board interrupts steam production and switches the green indicator lamp off. The disposable cylinder must be replaced.
It is wise to keep a new replacement cylinder on hand to avoid downtime when it becomes time to change the disposable cylinder.
MANUAL CAPACITY ADJUSTMENT
On/Off Controls
The SGH humidifier is rated in lbs/hr of steam output capacity. Set to 100%, it will operate at full output until the humidistat has sensed that the humidity has reached setpoint. Then it will stop the humidifier by breaking control circuit
If the humidifier is oversized, the humidistat will be quickly satisfied and stop the humidifier. As humidity level drops the humidistat calls again. It is quickly
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