Figure 2 - Chiller Control System - York YVAA Installation, Operation & Maintenance Instructions Manual

SECTION 2 - PRODUCT DESCRIPTION
INPUTS
Pressure Transducers
Temperature Sensors
Switches
Liquid Flow
High Pressure
Start/Stop
Level
Customer Supplied
Contacts
COMMUNICATIONS
Building Automation
Printer Modem
3 Phase Power Line
Rectifier
Signal From Main Control Panel

FIGURE 2 - CHILLER CONTROL SYSTEM

Oil separators utilize no moving parts.Oil cooling is
accomplished by refrigerant leaving the eductor flash-
ing in the suction line which cools the oil, motor and
compressor.
An integral liquid cooled, transistorized, PWM,
Variable Speed Drive (VSD) is controlled by the
chiller microprocessor control panel to start/stop, select
compressors to run, and select compressor speed.
Displacement Power Factor is 0. 95 at part or full load.
18
CONTROL
Chiller Control
Microprocessor
User Interface
Display and
DISPLAY
AC/DC Rectifier
Rectifier Controller
SCR Trigger Board
VSD Logic Board
PANEL
Board)
Keypad
KEYPAD
Power Driver
(IGBT)
IGBT Gate Driver
PWM Signal
The chiller microprocessor communicates with the
VSD Logic Board via a 3-wire RS-485 opto coupled
data link. The VSD Logic Board runs the number of
compressors required to meet the load and the com-
pressors to the speed requested by the chiller micro-
processor.
The basic system control and VSD system
architecture is shown in Figure 2 on Page 18.
FORM 201.28-NM1.1
ISSUE DATE: 1/31/2018
OUTPUTS
Relay Output Board)
Solenoids
Contactors
Alarm
Pump
Compressor Heater
Run Status
Evaporator Heater
VSD
VSD Logic Board
SCR Trigger Board
Power Components
PWM (Speed Control)
MOTOR
LD15028
Compressor 1
Compressor 2
Inverter
LD15158
JOHNSON CONTROLS