Datasheet

SF2D
5
ds_61404_en_sf2d: 180413D
THE OPERATION OF SF RELAYS (when contacts are welded)
SF relays work to maintain a normal operating state even when the contact welding occur by overloading or short-circuit
currents. It is easy to make weld detection circuits and safety circuits in the design to ensure safety even if contacts weld.
2 Form A 2 Form B type
If the form “b” contact (No. 1 and 3) welds, the armature becomes non-operational, the contact gaps at the three form “a” contacts are
maintained at greater than 0.5 mm .020 inch. Reliable isolation is thus ensured.
When the form “a” contacts (No. 2 or 4) weld, the armature remains in a non-returned state and the contact gap at the two form “b”
contact is maintained at greater than 0.5 mm .020 inch. Reliable isolation is thus ensured.
For Cautions for Use, see Relay Technical Information.
Form “b” Contact Weld
Form “a” Contact Weld
Contact Operation Table
No.4
No.3
No.1
No.2
Non-energized
No.4
No.3
No.1
No.2
Energized (when No. 1 contact is welded)
Example: If the No. 1 contact welds
Each of the three form “a” contacts (No. 2 and 4)
maintain a gap of greater than 0.5 mm .020 inch.
No.4
No.3
No.1
No.2
Energized
No.4
No.3
No.1
No.2
Non-energized (when No. 2 contact is welded)
Example: If the No. 2 contact welds.
The two form “b” contact (No. 1 or 3) maintains a gap of
greater than 0.5 mm .020 inch.
No.4
No.3
No.1
No.2
Contact No. No.1 No.2 No.3 No.4
Terminal No. 11–12 7–8 5–6 9–10
The table below shows the state of the other contacts when the current through
the welded form “a” contact is 0 V and the rated voltage is applied through the
form “b” contact.
* Contact gaps are shown at the initial state.
If the contacts change state owing to loading/breaking
it is necessary to check the actual loading.
State of other contacts
1234
Welded
terminal
No.
1 >0.5 >0.5
2 >0.5 >0.5
3 >0.5 >0.5
4 >0.5 >0.5
>0.5: contact gap is kept at
min. 0.5 mm .020 inch
Empty cells: either closed or open