144
FORM 160.54-M1
ISSUE DATE: 10/25/2019
SECTION 14 - ADAPTIVE CAPACITY CONTROL BOARD
JCI COMPANY CONFIDENTIAL
JOHNSON CONTROLS
The VSD consists of a Power Electronics Section,
Logic Board and an optional Harmonic Filter with
Harmonic Filter Logic Board, all mounted in a cabi-
net that is either mounted to the compressor motor or
floor standing (retrofit applications). The ACC Board
is mounted inside the OptiView Control Center. In op-
eration, the VSD Logic Board:
A. Controls the VSD power electronics to drive the
compressor motor at the speed designated by the
ACC Board.
B. Monitors power electronics parameters and initi-
ates chiller shutdowns when safety thresholds are
exceeded.
C. Transmits the parameters to the ACC Board for
transfer to the microboard for display.
The optional Harmonic Filter reduces the power line
harmonics produced by the VSD. The Harmonic Filter
Logic Board:
A.
Controls the filter.
B.
Monitors filter parameters and initiates chiller
shutdowns when safety thresholds are exceeded.
C. Transmits these parameters to the ACC Board for
transfer to the microboard for display.
Complete operation and service details of the VSD and
ACC Board is contained in
Variable Speed Drive – Ser-
vice Instructions (Form 160.00-M1)
and
Medium Volt-
age Variable Speed Drive – Service (Form 160.00-M6).
The microboard communicates with the ACC Board,
VSD Logic Board and the optional Harmonic Fil-
ter Logic Board via a 0 to +5 VDC 1200 baud serial
communications (
). The ACC
Board is the center point of communications between
the microboard and the VSD components. The com-
munications is in master/subordinate form. The VSD
Logic Board and Harmonic Filter Logic Boards act as
subordinates to the ACC. The ACC acts as a subordinate
to the microboard. The microboard initiates all com-
munications by sending a command to the ACC Board.
The ACC Board passes the command to the VSD Logic
Board. The VSD Logic Board responds to the com-
mand by returning the requested data to the ACC Board
and passes the command to the Harmonic Filter Logic
Board. The Harmonic Filter Logic Board returns the re-
quested data to the ACC Board. The ACC Board returns
both the VSD Logic Board’s response and the Harmonic
Filter’s response to the microboard.
There are three different commands issued from the mi-
croboard:
• Test and Initialize
• Fault Data Request
• Status Data Request
When power is first applied to the OptiView Control
Center, the microboard establishes serial communica-
tions with the ACC, VSD Logic and Harmonic Filter
Logic Boards. To establish communications, it sends a
Test and Initialize command to the ACC Board, which
sends the command on to the VSD Logic Board The
VSD Logic Board relays the command to the Harmonic
Filter Logic Board. If the VSD Logic and Harmonic
Filter Boards respond appropriately to the ACC Board,
the ACC Board responds to the microboard and com-
munications are established. If any of these boards fail
to respond to the first command, the microboard sends
the command again 4 seconds later. It will continue to
send this command at 4 second intervals until a response
is received. If, after 10 attempts, no response is received,
a cycling shutdown is performed and VSD –INITIAL-
IZATION FAULT is displayed. The microboard will
continue to establish communications until successful.
Anytime communications have been established and
then lost, the microboard will repeat this process to re-
establish communications.
After communications have been established, the mi-
croboard sends a Fault Data Request command. If
there have been any faults detected by the VSD Logic
or Harmonic Filter Boards since communications were
lost, they are returned to the microboard at this time. If
there is no response within 2 seconds, this command is
sent at 2 second intervals until a response is received. If
no response is received in 10 attempts, a cycling shut-
down is performed and VSD – SERIAL COMMUNI-
CATIONS is displayed.
The microboard then begins normal communica-
tions with the ACC, VSD Logic and Harmonic Filter
Boards. During normal communications, commands
and data are exchanged every 2 seconds on the serial
communications link. The microboard sends a Status
Data Request command every 2 seconds to the ACC
Board which is passed along to the VSD Logic Board
and Harmonic Filter Logic Boards as described above.
It expects to receive the data listed below in response to
each of these commands. If a response is not received
to 10 consecutive commands, a cycling shutdown is
performed and VSD – SERIAL COMMUNICATIONS
