Emerson Mobrey Series, Руководство по функциональной безопасности

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5
Functional Safety Manual
M310/FSM, Rev BA
Product Description
April 2017
Product Description
Section 2 Product Description
Note
For all product information and documentation downloads, see the on-line
Mobrey Magnetic Level Switch web page at
Emerson.com/Mobrey .
2.1 Operation principle
The level switch is designed to open or close a circuit (“switch”) as a changing liquid level within a vessel
passes the level of the float (the Switch Point).
When the process fluid level is below the Switch Point, contacts B-B are made and contacts A-A are open
(
Figure 2-1 on page 5 ).
When the process fluid level is above the Switch Point, contacts A-A are made and contacts B-B are open
(
Figure 2-2 on page 5 ).
Figure 2-1. Level Decreases – Float Pivots Downwards
Figure 2-2. Level Increases –Float Pivots Upwards
s
N
s
N
Contact B-B
Contact A-A
Pushrods
Float
Magnet
Float
Cross-section of the Level Switch
s
N
s
N
Contact B-B
Contact A-A
Pushrods
Float
Magnet
Float
Cross-section of the Level Switch