Limit Switches; Limit Switch Principles Of Operation; Limit Switch Types - Flowserve Logix 520MD Plus Series User Instructions

13 LIMIT SWITCHES

13.1 Limit Switch Principles of Operation

The Logix 520MD+ digital positioner can be equipped with
a limit switch unit. The unit has two main parts, the
electrical switch board and the vane. The switch board is
connected to the Inner cover. The vane connects to the
feedback shaft which extends through the positioner and
moves with the valve. The vane can hold a cam or
ferromagnetic device. As the shaft rotates, the pick-up
switch LS1 or LS2 is activated. The switching point can be
adjusted.
Four types of Limit Switches can be used with the Logix
520MD+.

13.2 Limit Switch Types

Mechanical switches are triggered by the use of a
mechanical cam and followers.
Reed switches are triggered by a magnetic force.
physical contact occurs.
Inductive Slot switches are triggered when the sensor
detects a ferromagnetic vane inserted between the coils.
No physical contact occurs.
Inductive switches are triggered when the sensor detects a
ferromagnetic vane approaching the coils in the switch. No
physical contact occurs.
Table 18: Limit Switch Cross-References
Information
Electronic
3.10
Connections
Electronic
7.10
Specifications
Install or Adjust the
16.2
Limit Switch
© Flowserve Corporation
User Instructions - Logix® 520MD+ Series Digital Positioner
IOM Section
Specifications
Limit Switch
Limit Switches
Installing a Limit Switch
Terminals
Limit
Switches
No
34
Field Trial Version – Printed October 28, 2011
FCD LGENIM0105-00
Figure 20: Limit Switches
Vane