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On applications where the compressor motor is driven by
the YORK Variable Speed Drive (VSD), the OptiView
Con trol center is equipped with an Adap tive Capacity
Con trol (ACC) Board (Fig. 42). This board performs
the fol low ing functions:
• Acts as a bi-directional serial com mu ni ca tions gate-
way between the Microboard and the VSD Logic
Board and VSD Harmonic Filter Logic Board.
• Tells the VSD Logic Board at what speed (fre-
quen cy) to operate the compressor motor. The speed
will be the lowest speed between 30 to 60 (50) Hz
it can operate without compressor surging.
• Detects Compressor surge conditions.
• Creates a Surge Map in battery backed memory by
storing the Pre-rotation Vanes (PRV) po si tion, mo tor
speed (frequency) and Evap o ra tor/Con dens er pres-
sure dif fer en tial (head) that exists when each surge
occurs.
The VSD consists of a power electronics section, Log ic
Board and an optional Harmonic Filter with Harmonic
Filter Logic Board, all mounted in a cabinet that is ei ther
mounted to the compressor motor or fl oor stand ing (ret-
ro fi t applications). The ACC Board is mounted inside the
OptiView Control Center. In operation, the VSD Logic
Board a.) controls the VSD power elec tron ics to drive the
com pres sor motor at the speed des ig nat ed by the ACC
Board, b.) monitors power elec tron ics pa ram e ters and
initiates chiller shutdowns when safety thresh olds are
exceeded and c.) transmits the parameters to the ACC
Board for transfer to the Microboard for display. The op-
tional Harmonic Filter re duc es the power line har mon ics
produced by the VSD. The Harmonic Filter Logic Board
a.) controls the fi lter b.) monitors fi lter parameters and
initiates chiller shut downs when safety thresholds are
exceeded and c.) trans mits these pa ram e ters to the ACC
Board for trans fer to the Microboard for dis play. Com-
plete operation and ser vice details of the VSD and ACC
Board is con tained in YORK man u al 160.00-M1.
The Microboard communicates with the ACC Board,
VSD Logic Board and the optional Harmonic Filter
Logic Board via 0/+5VDC 1200 baud serial com mu -
ni ca tions (Fig. 43). The ACC Board is the center point
YORK INTERNATIONAL
SECTION 12
ADAPTIVE CAPACITY CONTROL BOARD
(REFER TO FIG. 42 - 44)
of com mu ni ca tions between the Microboard and the
VSD com po nents. The communications is in master/
slave form. The VSD Logic Board and Harmonic Filter
Log ic Boards act as slaves to the ACC and the ACC acts
as a slave to the Microboard. The Microboard initiates
all communications 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
command 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 requested 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
Microboard: Test and Initialize, Fault Data Re quest
and Status Data Request. When power is fi rst ap plied to
the OptiView Control Center, the Microboard es tab lish es
se ri al communications with the ACC, VSD Logic and
Harmonic Filter Logic Boards. To establish com mu ni c-
a tions, it sends a Test and Ini tial ize com mand to the ACC
Board, which sends the command on to the VSD Logic
Board The VSD Logic Board relays the com mand to the
Harmonic Filter Logic Board. If the VSD Logic and Har-
mon ic Filter Boards respond ap pro pri ate ly to the ACC
Board, the ACC Board re sponds to the Microboard and
communications are es tab lished. If any of these boards
fail to re spond to the fi rst com mand, the Microboard
sends the command again 4 sec onds later. It will con-
tin ue to send this com mand at 4 second intervals until a
response is re ceived. If, after 10 attempts, no response
is re ceived, a Cycling shut down is performed and
VSD –INITIALIZATION FAULT is displayed. The
Microboard will con tin ue to establish com mu ni ca tions
until suc cess ful. Anytime com mu ni ca tions have been
es tab lished and then lost, the Microboard will repeat
this process to re-establish com mu ni ca tions.
After communications have been established, the
Microboard 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 re ceived.
FORM 160.54-M1(503)
12
75
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