Cautions for Use of Solid State Relays
ASCTB400E 201806-T
2) Tape and reel (AQ-H)
3) Tube
Snubber Circuit
Type
Tape dimensions (Unit: mm
inch
)
Dimensions of paper tape reel (Unit: mm
inch
)
8-pin SMD
type
(1) When picked from 1/2/3/4-pin side: Part No. AQH
❍❍❍❍
AX (Shown above)
(2) When picked from 5/6/8-pin side: Part No. AQH
❍❍❍❍
AZ
Tractor feed holes
Device mounted
on tape
Direction of picking
1.55
±
0.1
dia.
4.5
±
0.3
4
±
0.1
2
±
0.1
10.1
±
0.1
1.75
±
0.1
10.2
±
0.1
12
±
0.1
7.5
±
0.1
16
±
0.3
1.5
+
0.1
−
0
+
.004
−
0
.061
±
.004
dia.
.177
±
.012
.157
±
.004
.079
±
.004
.400
±
.004
.069
±
.004
.402
±
.004
.472
±
.004
.295
±
.004
.630
±
.012
.059
dia.
dia.
0.3
±
0.05
.012
±
.002
21
±
0.8
80
±
1
dia.
13
±
0.5
dia.
17.5
±
2.0
2
±
0.5
2
±
0.5
80
±
1
dia.
300
±
2
dia.
.827
±
.031
3.150
±
.039
dia.
.512
±
.020
dia.
.689
±
.079
.079
±
.020
.079
±
.020
3.150
±
.039
dia.
11.811
±
.079
dia.
Phototriac coupler and AQ-H SSR are packaged in a tube as pin
No. 1 is on the stopper B side. Observe correct orientation when
mounting them on PC boards.
<Phototriac coupler SOP type>
<Phototriac coupler DIP type and AQ-H SSR>
Stopper B (green)
Stopper A (gray)
Stopper B
Stopper A
1. Reduce dv/dt
An SSR used with an inductive load can accidentally fire due to
a high load voltage rise rate (dv/dt), even though the load
voltage is below the allowable level (inductive load firing).
Our SSRs contain a snubber circuit designed to reduce dv/dt
(except AQ-H).
2. Selecting the snubber constants
1) C selection
The charging coefficient tau for C of the SSR circuit is shown in
formula
1
τ
=(R
L
+R)
×
C ------------
1
By setting formula
1
so that it is below dv/dt value you have:
C=0.632V
A
/[(dv/dt)
×
(R
L
+R)] -----
2
By setting C = 0.1 to 0.2
μ
F, dv/dt can be controlled to between
nV/
μ
s and n+V/
μ
s or lower. For the condenser, use either an MP
condenser metallized polyester film. For the 100 V line, use a
voltage between 250 and 400 V, and for the 200 V line, use a
voltage between 400 and 600 V.
2) R selection
If there is no resistance R (the resistance R controls the
discharge current from condenser C), at turn-on of the SSR,
there will be a sharp rise in dv/dt and the high peak value
discharge current will begin to flow.
This may cause damage to the internal elements of the SSR.
Therefore, it is always necessary to insert a resistance R. In
normal applications, for the 100 V line, have R = 10 to 100
Ω
and
for the 200 V line, have R = 20 to 100
Ω
. (The allowable
discharge current at turn on will differ depending on the internal
elements of the SSR.) The power loss from R, written as P,
caused by the discharge current and charging current from C, is
shown in formula
3
below. For the 100 V line, use a power of
1/2 W, and for the 200 V line, use a power above 2 W.
------------
3
f = Power supply frequency
Also, at turn-off of the SSR, a ringing circuit is formed with the
capacitor C and the circuit inductance L, and a spike voltage is
generated at both terminals of the SSR. The resistance R serves
as a control resistance to prevent this ringing. Moreover, a good
non-inductive resistance for R is required. Carbon film resistors
or metal film resistors are often used.
For general applications, the recommended values are C = 0.1
μ
F and R = 20 to 100
Ω
. There are cases of resonance in the
inductive load, so the appropriate care must be taken when
making your selections.
Load power
supply
Inductive load
Snubber circuit
SSR
1
V
A
R
L
R
C
2
P= C
×
V
×
f
2
2
A
ー 9 ー
