Owner manual

Watlow EZ-ZONE
®
PM Integrated Controller • 152 • Chapter 10 Applications
Example 7: Wet Bulb / Dry Bulb
Requirements:
Two analog inputs and at least one output are required to adjust the controlled part of the processes.
Overview:
Wet Bulb/Dry Bulb is a configuration where a dry
bulb connected to Analog Input 1 measures tem-
perature on Analog Input 1. A wet bulb sensor that
is maintained with moisture has air moved over the
sensor. As moisture evaporates from the wet bulb, the
temperature drops. A wet bulb input on Analog In-
put 2, in combination with the dry bulb temperature,
senses relative humidity. The controller calculates
the temperature difference between the two sensors
to determine percent relative humidity. The humidify
and dehumidify outputs are disabled when Analog In-
put 1 temperature falls below 32 F/0 C, or goes above
212 F/100 C. When function is set for Wet Bulb/Dry
Bulb, the PV Function output equals calculated hu-
midity. Control loop 1 will control Analog Input 1 to
Closed Loop Set Point 1. Control loop 2 will control
Analog Input 2 to Closed Loop Set Point 2.
Example 8: Vaisala
Requirements:
Two analog inputs and the enhanced software option are required and at least two outputs adjusts the controlled
temperature and humidity processes.
Overview:
Vaisala Model HMM-30C Solid-state Relative
Humidity Sensor is supported with the Vaisala
configuration. Analog Input 1 is used to mea-
sure temperature and Analog Input 2 must be a
process input connected to a Vaisala sensor. The
controller provides temperature compensation
for the Vaisala sensor. The humidify and dehu-
midify outputs are disabled when Analog Input
1 temperature falls below -40 F/- 40 C, or goes
above 320 F/160 C. When function is set for Vais-
ala, the PV Function output equals the calculat-
ed relative humidity compensated by the sensor
on Analog Input 1.
Wet Bulb/Dry Bulb
Closed Loop
Set Point 2
Closed Loop
Set Point 1
Function
Filter
Source A
Source A
Source B
Source A
Heat Power
Heat Power
Cool Power
Cool Power
0 to 100%
0 to 100%
0 to 100%
0 to 100%
Output
Heat
Heat
Cool
Cool
Output n
Output n
Output n
Output n
Analog Input 1
Analog Input 2
Control Loop 2
Control Loop 1
PV Function
Temperature
Humidity
Vaisala
Closed Loop
Set Point 2
Closed Loop
Set Point 1
Function
Filter
Source A
Source A
Source B
Source A
Heat Power
Heat Power
Cool Power
Cool Power
0 to 100%
0 to 100%
0 to 100%
0 to 100%
Output
Heat
Heat
Cool
Cool
Output n
Output n
Output n
Output n
Analog Input 1
Analog Input 2
Control Loop 2
Control Loop 1
PV Function
Temperature
Humidity