www.DaikinApplied.com
5
IOM 1210-7 • MAGNITUDE
®
MODEL WMC CHILLERS
I
nTroduCTIon
The Control System
The centrifugal MicroTech
®
II control system consists
of a human machine interface touch screen (HMI), a
microprocessor-based unit controller, and compressor on-
board controllers, providing monitoring and control functions
required for the efficient operation of the chiller.
Human Machine Interface
The human machine interface (HMI) screen, (see
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 HMI
panel can be downloaded via a USB port located on the side of
the touchscreen panel.
A single HMI is used per unit. The HMI panel, see
, is mounted on a moveable arm to allow placement in a
convenient position for the operator. The HMI PC is located in
the Control Panel, as shown in
on the HMI, see
“Machine Interface Screen (HMI)” on page
Figure 2: Machine 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
for more
information.
The controller is located in the control panel, as shown in
. It has a 4x20 LCD display and keys for accessing
data and changing setpoints. The controller sends information
to the machine interface touch screen (HMI) for graphic
display. If the HMI should become inoperable, the controller
LCD can display most of the same information as the HMI and
can be used to operate the chiller independently of the HMI.
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 HMI 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
HMI PC
Switch
Bracket
1
2
