SF
POLARISED, MONOSTABLE
SAFETY RELAY with
(mechanical linked) forced
contacts operation
π
53.3±0.3
2.098±.012
25.0
.984
16.5±0.3
.650±.012
(SF3 pending) (SF3 pending)
(SF3 pending)
SF-RELAYS
enables to plan a circuit to detect welding
or go back to the beginning condition.
• Separated chamber structure
(2 Form A 2 Form B, 3 Form A 1 Form B,
4 Form A 4 Form B)
N.O. and N.C. side contacts are put in
each own space surrounded with a card
and a body-separater. That prevents
short circuit between contacts, which is
caused by their springs welding or
damaged.
• UL/CSA, TÜV, SEV approved
(UL/CSA, SEV of SF3 pending)
FEATURES
• Forced operation contacts (2 Form A
2 Form B, 3 Form A 1 Form B)
N.O. and N.C. side contacts are
connected through a card so that one
interacts with the other in movement. In
case of a contact welding, the other
keeps a min. 0.5mm
.020inch
contact
gap.
• Independent operation contacts
(4 Form A 4 Form B)
Each pair of contacts is free from the
main armature and is independent from
each other. So if a N.O. pair of contacts
are welded, the other 3 N.O. contacts are
not effected (operate properly) That
53.3±0.3
2.098±.012
25.0
.984
16.5±0.3
.650±.012
53.3±0.3
2.098±.012
33±0.3
1.299±.012
16.5±0.3
.650±.012
mm
inch
SPECIFICATIONS
Contact
Type
Arrangement
Initial contact resistance, max.
(By voltage drop 6 V DC 1 A)
Contact material
Nominal switching
capacity
Rating
Max. switching power
(resistive)
Max. switching voltage
Max. carrying current
Mechanical (at 180
Expected
cpm) (resistive)
life (min.
operations) Electrical (at 20 cpm)
SF2
SF3
SF4
2 Form A 3 Form A 4 Form A
2 Form B 1 Form B 4 Form B
30 m
Ω
Gold-flashed silver alloy
6 A 250 V AC, 6 A 30 V DC
1,500 VA, 180 W
30 V DC, 440 V AC
6 A DC, AC
10
7
3
×
10
4
*
1
10
5
Characteristics
(at 25°C
77°F
, 50% Relative humidity)
Max. operating speed
Initial insulation resistance*
2
Between con-
tact sets
Initial break-
Between open
down voltage*
3
contacts
Between con-
tact and coil
Operate time*
4
(at nominal voltage)
Release time (without diode)*
4
(at nominal voltage)
Temperature rise
(at nominal voltage)
Functional*
5
Shock
resistance
Destructive*
5
Vibration
resistance
Conditions for oper-
ation, transport and
storage*
8
(Not freezing and
condensing at low
temperature)
SF2
SF3
SF4
180 cpm (at nominal voltage)
Min. 1,000 M
Ω
at 500 V DC
2,500 Vrms
2,500 Vrms
2,500 Vrms
Approx. 17 ms
Approx. 7 ms
Approx. 18 ms
Approx. 6 ms
Coil
(at 25°C
77°F
)
Nominal operating power
Remarks
* Specifications will vary with foreign standards certification ratings.
*1
500 mW
Functional*
7
Destructive
Ambient
temp.
Humidity
More than 10
5
operations when applying the nominal switching capacity to one
side of contact pairs of each Form A contact and Form B contact
*2
Measurement at same location as " Initial breakdown voltage " section
*3
Detection current: 10mA
*4
Excluding contact bounce time
*5
Half-wave pulse of sine wave: 11ms; detection time: 10
µ
s
*6
Half-wave pulse of sine wave: 6ms
*7
Detection time: 10
µ
s
*8
Refer to 5. Conditions for operation, transport and storage mentioned in
AMBIENT ENVIRONMENT (Page 61).
Max. 45
°
C with nominal coil voltage
and at 6 A switching current
Min. 294 m/s
2
{30 G}
Min. 980 m/s
2
{100 G}
117.6 m/s
2
{12 G}, 10 to 55 Hz
at double amplitude of 2 mm
117.6 m/s
2
{12 G}, 10 to 55 Hz
at double amplitude of 2 mm
–40
°
C to +70
°
C
–40°F to +158°F
5 to 85% R.H.
37 g
1.31 oz
47 g
1.66 oz
Unit weight
ORDERING INFORMATION
Ex. SF
2
DC 12 V
Coil voltage
DC 5, 9, 12, 18, 21,
24, 36, 48, 60 V
Contact arrangement
2: 2 Form A 2 Form B
3: 3 Form A 1 Form B
4: 4 Form A 4 Form B
TYPICAL APPLICATIONS
• Signal
• Escalator
• Elevator
• Medical Instruments
• Railway
• Factory Automation
UL/CSA, TÜV, SEV approved type is standard (SF2, SF4)
TÜV approved type is standard (SF3)
258
SF
TYPES AND COIL DATA (at 20°C
68°F)
Contact
arrangement
Part No.
SF2-DC5V
SF2-DC9V
SF2-DC12V
SF2-DC18V
SF2-DC21V
SF2-DC24V
SF2-DC36V
SF2-DC48V
SF2-DC60V
SF3-DC5V
SF3-DC9V
SF3-DC12V
SF3-DC18V
SF3-DC21V
SF3-DC24V
SF3-DC36V
SF3-DC48V
SF3-DC60V
SF4-DC5V
SF4-DC9V
SF4-DC12V
SF4-DC18V
SF4-DC21V
SF4-DC24V
SF4-DC36V
SF4-DC48V
SF4-DC60V
Nominal
voltage, V DC
5
9
12
18
21
24
36
48
60
5
9
12
18
21
24
36
48
60
5
9
12
18
21
24
36
48
60
Pick-up
voltage, VDC
(max.)
3.75
6.75
9
13.5
15.75
14.4
27
36
45
3.75
6.75
9
13.5
15.75
14.4
27
36
45
3.75
6.75
9
13.5
15.75
14.4
27
36
45
Drop-out
voltage, V DC
(min.)
0.5
0.9
1.2
1.8
2.1
2.4
3.6
4.8
6.0
0.5
0.9
1.2
1.8
2.1
2.4
3.6
4.8
6.0
0.75
0.9
1.8
1.8
2.1
3.6
3.6
7.2
9.0
Coil
resistance
Ω
(
±
10%)
50
288
Nominal
operating
current,
mA(
±
10%)
100
41.7
Nominal
operating
power, mW
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
500
Max. allowable
voltage, V DC
6
10.8
14.4
21.6
25.2
28.8
43.2
57.6
72
6
10.8
14.4
21.6
25.2
28.8
43.2
57.6
72
6
10.8
14.4
21.6
25.2
28.8
43.2
57.6
72
SF2
1.152
4.608
7.200
50
288
20.8
10.4
8.3
100
41.7
SF3
1.152
4.608
7.200
50
288
20.8
10.4
8.3
100
41.7
SF4
1.152
4.608
7.200
20.8
10.4
8.3
DIMENSIONS
1) SF2
16±0.3
.630±.012
2
mm
inch
Schematic (Bottom view)
5
1
6
7
8
0.5
.020
5.08
.200
12.7
.500
12.7
.500
53.3±0.3
2.098±.012
5
6
7
8
9
10
11
12
12.7
.500
3.5±0.3
.138±.012
PC board pattern (Bottom view)
2.54
.100
10-1.4 DIA. HOLES
10-.055 DIA. HOLES
25.0
.984
7.62
.300
2.54
.100
12.7
.500
1
2
9
10
11
12
General tolerance:
±0.3
±.012
Tolerance:
±0.1
± .004
259
SF
2) SF3
Schematic (Bottom view)
5
1
16±0.3
.630±.012
2
0.5
.020
5.08
.200
12.7
.500
12.7
.500
53.3±0.3
2.098±.012
5
6
7
8
mm
inch
6
7
8
9
10
11
12
12.7
.500
3.5±0.3
.138±.012
PC board pattern (Bottom view)
2.54
.100
10-1.4 DIA. HOLES
10-.055 DIA. HOLES
25.0
.984
7.62
.300
2.54
.100
12.7
.500
1
2
9
10
11
12
General tolerance:
±0.3
±.012
Tolerance:
±0.1
±.004
3) SF4
Schematic (Bottom view)
13
16±0.3
.630±.012
0.3
.012
5.08
.200
12.7
.500
12.7
.500
53.3±0.3
2.098±.012
13
5
1
14
6
15
7
16
8
14
15
16
1
5
9
2
17
18
19
20
6
10
7
11
8
12
12.7
.500
3.5±0.3
.138±.012
33±0.3
1.299±.012
7.62
.300
7.62
.300
12.7
.500
PC board pattern (Bottom view)
2.54
.100
2.54
.100
18-1.4 DIA. HOLES
18-.055 DIA. HOLES
2
9
17
10
18
11
19
12
20
7.62
.300
General tolerance:
±0.3
±.012
Tolerance:
±0.1
±.004
REFERENCE DATA
1. Operate/release time
2. Coil temperature rise
Coil applied voltage: 120%V
Contact switching current: 6A
50
Operate/release time, ms
60
50
40
-40 -20
30
20
Contact
10
Max.
x
Min.
90
100
110
120
Coil applied voltage, %V
Release time
0
-100
-50
Inside the coil
0
20 40
3. Ambient temperature characteristics
Tested sample: SF4-DC12V
Quantity: n = 6
Rate of
change, %
100
Drop-out
voltage
50
Pick-up
voltage
60 80
Ambient
temperature,
°C
40
30
Operate time
20
Max.
x
Min.
10
0
Temperature rise,
°C
80
30
50
70
Ambient temperature,
°C
260
SF
SAFETY STRUCTURE OF SF RELAYS
This SF relay design ensures that
subsequent operations shut down and can
automatically return to a safe state when
the SF relay suffers overloading and other
circuit abnormalities (unforeseen
externally caused circuit or device
breakdowns, end of life incidents, and
noise, surge, and environmental
influences) owing to contact welding,
spring fusion or, in the worst-case
Structure
Min. 0.5 mm
.020 inch
scenario, relay breakdown (coil rupture,
faulty operation, faulty return, and fatigue
and breakage of the operating spring and
return spring), and even in the event of
end of life.
Operation
Contact a
Card
Even when one contact is welded closed,
the other maintains a gap of greater than
0.5 mm
.020 inch.
In the diagram on the left, the lower
contact "b" have welded but the upper con-
tact "a" maintain at a gap of greater than
0.5 mm
.020 inch.
Subsequent contact movement is
suspended and the weld can be detected
1. Forced operation method
(2a2b, 3a1b, 4a4b types)
Weld
Contact b
The two contacts “a” and “b” are coupled with the same
card. The operation of each contact is regulated by the
movement of the other contact.
External NO
contact weld
Return
Enables design of safety circuits that allow
weld detection and return at an early stage.
2. Independent operation method
(4a4b type)
Return
Return
None of four contacts are held in position by the armature.
Even though one of the external N.O. contacts has
welded, the other three contacts have returned owing to
the de-energizing of the coil.
As shown at the top right of the diagram on
the left, if the external N.O. contact welds, a
0.5 mm
.020 inch
gap is maintained.
Each of the other contacts returns to N.O.
because the coil is no longer energized.
In independent chambers, the contacts "a" and "b" are
kept apart by a body/card separator or by the card itself.
Case separator
1
Card
Contact a
2
Body
separator
Contact b
Prevents shorting and fusing of springs and
spring failure owing to short-circuit current.
As shown on the diagram on the left, even
if the operating springs numbered 1 and 2
there is no shorting between "a" and "b"
contacts.
3. Separate chamber method
(2a2b, 3a1b, 4a4b types)
4. High-efficiency 4-gap balanced
armature structure
(2a2b, 3a1b, 4a4b types)
The use of high-efficiency magnetically polarized circuits
and 4-gap balanced armature structure means that
springs are not required.
Does away with return faults due to fatigue
or breakage of the return spring, especially
stoppage during contact states.
5. 2a2b contact
3a1b contact
4a4b contact
Structure with independent COM contact of (2a2b),
(3a1b), (4a4b) contacts.
Independent COM enables differing pole
circuit configurations. This makes it
possible to design various kinds of control
circuits and safety circuits.
261
SF
THE OPERATION OF SF RELAYS (when contacts are welded)
SF relays work to maintain a normal operating state even when overloading or short-circuit currents occur. It is also easy to include
weld detection circuits and safety circuits in the design to ensure safety even if contacts weld.
1) 2a2b Type
Form “b” Contact Weld
If the form “b” contacts (Nos. 1 and 3) weld, the armature becomes non-operational and the contact gap of the two form “a” contacts
is maintained at greater than 0.5 mm
.020 inch.
Reliable isolation is thus ensured.
No.4
No.1
No.4
No.1
If the No. 1 contact welds.
A gap of greater than 0.5 mm
.020 inch
is main-
tained at each of the two form "a" contacts (Nos.
2 and 4).
No.3
No.2
No.3
No.2
Non-energized
Energized (when no. 1 contact is welded)
Form “a” Contact Weld
If the two form “a” contacts (Nos. 2 and 4) weld, the armature becomes non-operational and the gap between the two form "b"
contacts is maintained at greater than 0.5 mm
.020 inch.
Reliable isolation is thus ensured.
No.4
No.1
No.4
No.1
If the No. 2 contact welds.
Each of the two form "b" contacts (Nos. 1 and 3)
maintains a gap of greater than 0.5 mm
.020 inch.
No.3
No.2
No.3
No.2
Energized
Non-energized (when no. 2 contact is welded)
Contact Operation Table
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 No.
Contact No.
1
Welded
2
terminal
3
No.
4
No.4
No.1
No.3
No.2
State of other contacts
1
2
3
4
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5
>0.5: contact gap is kept at min. 0.5 mm
.020 inch
Empty cells: either closed or open
Contact No.
Terminal No.
No.1
11–12
No.2
7–8
No.3
5–6
No.4
9–10
Note: 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.
262
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