Figure 73 - Variable Geometry Diffuser Block Diagram - Johnson Controls YORK OPTIVIEW YK Series Service Instructions Manual

SECTION 25 - VARIABLE GEOMETRY DIFFUSER
ent. When it reaches the value programmed as the
High Limit setpoint (typically set to 0.8VDC), the
VGD closes until the voltage decreases to the Low
Limit setpoint (typically set to 0.6VDC). Since
the filter causes the STALL DETECTOR VOLT-
AGE to typically run 0.2 to 0.3VDC lower than
Standard Mode for the same condition, it may be
necessary to lower the High Limit and Low Limit
setpoints if valid stall conditions are not being de-
tected or surge occurs before stall is detected. Ide-
ally, stall should be detected before surge occurs,
allowing the VGD to react prior to surge. Also,
STALL
TRANSDUCER
NOTE:
Requires I/O Board 031-01743-002
* Refer to PIN Connections above

FIGURE 73 - VARIABLE GEOMETRY DIFFUSER BLOCK DIAGRAM

202
STALL
DETECTOR
BOARD
STALL
J1 J1 J2
DETECTOR
+5 Vdc OUTPUT
3 1 4
*
GND
OUT
1 2 3
*
+5 Vdc
GND
2 3 1
*
STALL
TRANSDUCER
OUTPUT
2
NOTES:
1. Requires I/O Board 031-01743-002
since the PRV Position – VGD Inhibit Setpoint
was the original vehicle to avoid VGD reaction to
high gas flow/low head conditions, this setpoint
should be set to 95% or 100% to avoid interfer-
ence when Enhanced Mode is selected.
• STANDARD Mode – This mode should not be
used unless under the advisement of Johnson
Controls technical support. Provides the same
operation as the 031-02418-000 board. Does not
filter high gas flow/low head noise conditions as
described in enhanced mode above.
MICRO I/O
BOARD BOARD
J7 TB1
23 158
J19 J1
Open
31 31
24 159
Close
30 30
12 160
J8
SEE NOTE 1
1
FORM 160.54-M1
VGD
ACTUATOR
2
1
3
LD09467b
JOHNSON CONTROLS