Cautions for Use of Solid State Relays
ASCTB400E 201806-T
Load Inrush Current Wave and Time
SSR Driving Circuits
(1) Incandescent Lamp Load
(2) Mercury Lamp Load
i/i
O
]
3 times
(3) Fluorescent Lamp Load
i/i
O
]
5 to 10 times
(4) Motor Load i/i
O
]
5 to 10 times
(5) Solenoid Load
i/i
O
]
10 to 20 times
(6) Electromagnetic Contact Load
i/i
O
]
3 to 10 times
(7) Capacitive Load
i/i
O
]
20 to 40 times
i
Approx. 1/3 second
Inrush current/rated current:
i/i
o
]
10 to 15 times
Incandescent lamp
i
o
i
i
o
3 to
5 minutes
The discharge tube, transformer, choke coil,
capacitor, etc., are combined in common
discharge lamp circuits. Note that the inrush
current may be 20 to 40 times, especially if
the power supply impedance is low in the
high power factor type.
Contacts
L
C
(for high power factor type)
i
o
i
10 seconds
or less
i
o
i
0.2 to 0.5 second
• Conditions become more harsh if plugging or inching
is performed since state transitions are repeated.
• When using a relay to control a DC motor and brake,
the on time inrush current, steady-state current and
off time brake current differ depending on whether
the load to the motor is free or locked. In particular,
with non-polarized relays, when using from B contact
of from contact for the DC motor brake, mechanical
life might be affected by the brake current.
Therefore, please verify current at the actual load.
Free
Lock
Load
Starting
Steady
state
Braking
i
o
0.07
to 0.1 second
i
Note that since inductance is great,
the arc lasts longer when power is cut.
The contact may become easily worn.
i
o
1 to 2 cycles
(1/60 to 1/30 seconds)
i
i
o
1/2 to 2 cycles (1/120 to 1/30 seconds)
i
1. Relay Driver
2. NPN Transistor Driver
3. PNP Transistor Driver
Load
Load power
supply
Relay contacts
Vcc
SSR
1
2
3
4
Vcc
Load
SSR
NPN Transistor
1
2
3
4
Load power
supply
Vcc
Load
SSR
1
PNP Transistor
2
3
4
Load power
supply
4. TTL/DTL/IC Driver
5. C-MOS/IC Driver
(1) SSR fires when IC output is HIGH:
(2) SSR fires when IC output is LOW:
Vcc
Load
SSR
TTL, DTL, IC
1
2
3
4
Load power
supply
Vcc
Load
SSR
1
2
3
4
C-MOS IC
Load power
supply
Vcc
Load
SSR
1
2
3
4
C-MOS IC
Load power
supply
ー 12 ー
