Rockwell Automation Low-Voltage Switchgear and Controlgear - Manual (Page 67)

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Fig. 2.4-11
The make contacts remain open when mechanically linked when the control relay is excited and a break
contact has welded.
In accordance with standard, mechanically linked contacts should be clearly labeled on the
device or in the documents or in both places.
Fig. 2.4-12 shows the symbols to be used.
Fig. 2.4-12
Symbol for mechanically linked contacts together with contacts that are not mechanically linked (left) and
symbol for mechanically linked contacts, when all contacts are mechanically linked (right)
2.4.6.2 Mirror Contacts
Appendix F of IEC 60947-4-1 defines the requirements for mirror contacts, i.e. for the unambi-
guous feedback of the state of the main contacts in event of fault, for example with welded main
contacts. The standard defines a mirror contact as “normally closed auxiliary contact which
cannot be in closed position simultaneously with the normally open main contact under condi-
tions defined ….”, i.e. if a main contact has welded. The test conditions are similar to those for
mechanically linked contacts: The auxiliary normally closed contacts that are designed as mirror
contacts must still have an opening clearance of 0.5 mm or be able to withstand a test impulse
voltage of 2.5 kV when the contactor is de-energized.
LVSAM-WP001A-EN-P - April 2009 2-39