Chapter 10: Applications; Example 1: Single Loop Control; Example 2: Sensor Backup; Example 3: Square Root - Watlow EZ-ZONE PM User Manual

Chapter 10: Applications

With the release of version 7.00 firmware several new
functions were added to the EZ-ZONE PM family of
controls. This chapter contains some sample applica-
tions using these new functions.

Example 1: Single Loop Control

Requirements:
One input is required and at least one output adjusts
the controlled part of the process.
Overview:
Controls one process value to a user entered Closed
Loop Set Point based on an control algorithm.
Control loop 1 will control Analog Input 1 to Closed
Single Loop Control
Analog Input 1
Source A
Loop Set Point 1.

Example 2: Sensor Backup

Requirements:
Two analog inputs and the enhanced software option
are required and at least one output adjusts the con-
trolled part of the process.
Overview:
The Sensor Backup feature controls a process based
on a primary sensor on Analog Input 1. If this sensor
fails, then the process is controlled based on the sec-
ondary sensor on Analog Input 2.
When function is set for Sensor Backup, the PV Func-
tion output equals Source A if sensor of Analog Input 1
Sensor Backup
Analog Input 1 Source A
Analog Input 2 Source B Output
PV Function
Source A
Control Loop 1
®
Wat l o w EZ -ZON E PM In t e g r a te d Co n t r o lle r
Output n
0 to 100%
Heat Power
Cool Power
Control Loop 1
0 to 100%
Output n
Output n
0 to 100%
Heat
Heat Power
Cool Power
Cool
0 to 100%
Output n
reading is valid or Source B if sensor reading is invalid.
Control loop 1 will control the valid Analog Input sensor
to Closed Loop Set Point 1.

Example 3: Square Root

Requirements:
One analog input and the enhanced software option
are required and at least one output adjusts the con-
trolled part of the process.
Overview:
Calculates the square root value of the sensor connect-
ed to Analog Input 1.
When function is set for Square Root, the PV Function
output equals square root value of Source A. Control
loop 1 will control Analog Input 1 to Closed Loop Set
Point 1.
Heat
Cool
Analog Input 1

Example 4: Ratio

Requirements:
Two analog inputs and the enhanced software option
are required and at least one output adjusts the con-
trolled part of the process.
Overview:
The Ratio feature allows control of one process as a
ratio of another process. This is especially useful in
applications that mix two materials, whether steam,
paint or food ingredients. Analog Input 1 monitors the
controlled part of the process. Analog Input 2 of the
controller measures the part of the process that is ei-
ther uncontrolled or controlled by another device. The
part of the process controlled will be maintained at a
level equal to the quantity measured at input 2 mul-
tiplied by the ratio term set by the user as Closed Set
Point 1.
1 1 5
• •
Square Root
Source A
Output
PV Function
0 to 100%
Source A Heat Power
Cool Power
Control Loop 1
0 to 100%
Chapter 10 Ap pli ca tions
Output n
Heat
Cool
Output n