MKS 41A - Method of Operation; Units Set to Energize above the Trip Point Pressure; Figure 9: Trip Point Set to Energize above the Trip Point Pressure; Table 6: Trip Point Signals

Method of Operation Cha
p
ter Three: Overview
20
Method of Operation
The 41/42/51/52 pressure switch changes the state of a relay when the pressure crosses the trip
point pressure. The pressure switch is set at the factory in one of two settings:
Relay energizes when the pressure
rises above
the trip point pressure
or
Relay energizes when the pressure
drops below
the trip point pressure
Note
The action of the switch (whether the relay is energized when the pressure
rises above or drops below the trip point pressure) cannot be changed in the
field.
The trip point signal is available on the connector as shown in Table 6. (For complete connector
assignments, refer to Table 4, page 11, and Table 5, page 12.)
Trip Point Signals
Pin Number Flying Lead Color Assignment
3 Green Relay Normally Open Contact
4 White Relay Common
5 Orange Relay Normally Closed Contact
Table 6: Trip Point Signals
Units Set to Energize
Above
the Trip Point Pressure
When the measured pressure is below the trip point value, the relay is in its normal state; the
normally open contact is open and the normally closed contact is closed. When the pressure rises
above the trip point value, the relay changes to its tripped state; the normally open contact closes
and the normally closed contact opens.
Ener
g
ize When Pressure Rises Above the Tri
p
Point Pressure
Trip Point
Pressure
Increasin
g
Pressure
Relay State: Normal (de-ener
g
ized)
Normally Open contact is open
Normally Closed contact is closed
Relay State: Tripped (ener
g
ized)
Normally Open contact is closed
Normally Closed contact is open
Figure 9: Trip Point Set to Energize Above the Trip Point Pressure