FX3U Series Programmable Controllers
User’s Manual - Hardware Edition
53
4 Specifications, External Dimensions and Terminal Layout (Main Units)
4.1 Generic Specifications
1
Introduction
2
Features and 
Part Names
3
Product 
Introduction
4
Specifications
5
Version and 
Peripheral 
Devices
6
System 
Configuration
7
Input/Output 
Nos., Unit Nos.
8
Installation
9
Preparation and 
Power Supply 
Wiring
10
Input Wiring
4.1.1 Dielectric withstand voltage test and insulation resistance test
Perform dielectric withstand voltage test and insulation resistance test at the following voltage between each
terminals and the main unit ground terminal.
Between terminals
Dielectric
strength
Insulation
resistance
Remarks
Terminals of main unit and input/output powered extension unit/block
• Between power supply terminal (AC 
power supply) and ground terminal
1.5kV AC 
for 1 min
5M Ω or 
more on 
500V DC 
Megger
−
• Between power supply terminal (DC 
power supply) and ground terminal
500V AC for 
1 min
−
• Between 24V DC service power supply 
connected to input terminal (24V DC) 
and ground terminal
500V AC for 
1 min
−
• Between input terminal (100V AC) and 
ground terminal
1.5kV AC 
for 1 min
−
• Between output terminal (relay) and 
ground terminal
1.5kV AC 
for 1 min
−
• Between output terminal (transistor) 
and ground terminal
500V AC for 
1 min
−
• Between output terminal (triac) and 
ground terminal
1.5kV AC 
for 1 min
−
Terminals of expansion board, special adapter and special function unit/block
• Between terminal of expansion board
(except for the FX3U-USB-BD and
FX3U-CNV-BD) and ground terminal
Not allowed Not allowed
Since the expansion board and the main unit
CPU are not insulated, it is not allowed to
perform the dielectric withstand voltage test
and insulation resistance test between them.
• Between terminal of expansion board
(FX3U-USB-BD) and ground terminal
Not allowed Not allowed
Do not perform the dielectric withstand
voltage test and insulation resistance test
between the communication line and the main
unit CPU.
• Between terminal of special adapter
and ground terminal
500V AC for 
1 min
5M Ω or 
more on 
500V DC 
Megger
−
• Special function unit/block Each manual
Refer to the manual for each special function
unit/block.