www.DaikinApplied.com
5
IOM 1210-1 • MAGNITUDE
®
MODEL WMC CHILLERS
I
nTroduCTIon
The Control System
The centrifugal MicroTech
®
II control system consists of an
operator interface touch screen (OITS), a microprocessor-
based unit controller, and compressor on-board controllers,
providing monitoring and control functions required for the
efficient operation of the chiller.
Operator Interface Touch Screen
The operator interface touch screen (OITS), see
Figure 2
for an example of a screen display, is the primary device for
viewing unit operation information and entering commands
and entries into the control system. Select information from the
OITS panel can be downloaded via a USB port located in the
unit control panel.
A single OITS is used per unit. The OITS panel, see
Figure
1
, is mounted on a moveable arm to allow placement in a
convenient position for the operator. The OITS PC is located in
the Control Panel, as shown in
Figure 3
. For more information
on the OITS, see the
“Operator Interface Touch Screen (OITS)”
section starting on
page 21
.
Figure 2: Operator Interface Touch Screen
Unit Controller
The purpose of the MicroTech
®
II unit controller is to acquire
and process data relating to chiller operation, issue instructions
to various components of the chiller, and maintain controlled
operation of the chiller. As a part of operating the chiller
successfully, the unit controller offers necessary condenser
water control. See
“Condenser Water Temperature Control” on
page 9
for more information.
The controller is located in the control panel, as shown in
Figure 3
. It has a 4x20 LCD display and keys for accessing
data and changing setpoints. The controller sends information
to the operator interface touch screen (OITS) for graphic
display. If the OITS should become inoperable, the controller
LCD can display most of the same information as the OITS and
can be used to operate the chiller independently of the OITS.
See
“The Controller”
section on
page 48
for information.
Figure 3: Control Panel
Compressor On-Board Controllers
Each compressor is equipped with microprocessor controllers
and sensors that provide control and data acquisition. The data
is transmitted to other controllers and the OITS via the multi-
unit communication network. The on-board controllers control
compressor functionality and the motor/bearing system.
Figure 4: Compressor Cutaway
1. Power Electronics
2. Control Electronics
MicroTech
®
II
Controller
OITS PC
1
2
