9
Model 289A Differential Pressure Indicating Switch
Section 2
Switch and Relay Wiring Diagrams
IMPORTANT: Figures 2.1 through 2.6 show: switch & relay contacts in the relaxed
(shelf) condition, the low switch set to trip at a position below the pointer
scale position, and the high switch set to trip at a position above the
pointer scale position. NO = Normally Open in (shelf) condition. NC =
Normally Closed in (shelf) condition. C= Common.
HIGH SPDT SWITCH
NO
C
NC
CASE GR
OUND
GREEN
OR
ANGE
VIOLE
T
BLA
CK
OR
ANGE
VIOLE
T
BLA
CK
8
9 10
LOW SPDT SWITCH
NO
1
2
3
C NC
RED
YELL
OW
BL
UE
RED
CASE GR
OUND
GREEN
YELL
OW
BL
UE
LOW & HIGH SPDT SWITCHES
NO
NO
C
C
NC
NC
RED
YELL
OW
BL
UE
RED
CASE GR
OUND
GREEN
YELL
OW
BL
UE
OR
ANGE
VIOLE
T
BLA
CK
OR
ANGE
VIOLE
T
BLA
CK
1
2
3
4
5
6
7
8
9 10
Figure 2.1—Low/high SPDT switch diagrams
(current configuration color codes - see
Table 2.1, page 8
)