Emerson Rosemount 3490 Series Reference Manual page 108

Getting started
January 2021
Figure 4-35: Pump 1 is Off and Pump 2 is On (Rising Level Above 8 m)
E
A. Level in m
B. 8.0 m (P421)
C. 5.0 m (P411)
D. 2.0 m (P412)
E. Pump 1
F. Pump 2
When the level falls to below 5 m (Off point, P422), relay RL2 de-energizes to switch off
Pump 2. Relay RL1 is energized to switch on Pump 1
Figure 4-36: Pump 1 is On and Pump 2 is Off (Falling Level Below 5 m)
E
A. Level in m
B. 8.0 m (P421)
C. 5.0 m (P411)
D. 2.0 m (P412)
E. Pump 1
F. Pump 2
In this emptying application, the switch off point for Pump 2 is 5 m; the On Point for relay 1
P411 (On point, relay RL1) is used. P422 (Off point, relay RL2) is ignored.
When the level falls below 2 m (Off point, P412), relay RL1 de-energizes to switch off Pump
1.
108
A
B
C
D
F
A
B
C
D
F
Reference Manual
00809-0100-4841
(Figure 4-36).
Emerson.com/Rosemount