Applying Safe Loads - Mitsubishi FX1N-14MR-ES/UL Hardware Manual

FX1N Series Programmable Controllers
6.4

Applying Safe Loads

Caution for DC Loads
1) Relay output case
This PLC does not have any internal protection
circuitry on the relay outputs. For switching direct
current on inductive loads, a reverse-current
protection diode should be installed in parallel with
t h e l o a d . T h e r e l ay c o n t a c t l i fe d e c r e a s e s
significantly if this is not done.
The reverse-current protection diode needs to
satisfy the following specifications.
- The diode is rated for maximum reverse voltage of 5 to 10+ times the load voltage.
- The forward current is more than the load current.
2)Transistor output case
Transistor outputs use internal zener diode (50V)
as protection circuitry. When driving the inductive
load with transistor output, a reverse-current
protection diode can be installed in parallel with the
load if necessary.
The reverse-current protection diode needs to
satisfy the following specifications.
- The diode is rated for maximum reverse voltage of 5 to 10+ times the load voltage.
- The forward current is more than the load current.
DC (+)
Inductive load
Reverse-current
PLC output
protection diode
DC (+)
Inductive load
Reverse-current
PLC
protection diode
output
6-6
Outputs 6.
DC (-)
DC (-)