38
6 INSTALLATION AND EXTERNAL WIRING
6.2 External Wiring
Measures to reduce noise
The flexible high-speed I/O control module may malfunction if pulse-like noise is input. Thus, take the following measures to
reduce noise:
• Always use a shielded twisted pair cable.
• Arrange a shielded twisted pair cable keeping a distance of 150mm or more from the power cable, I/O cables, or other
cables that cause much noise. Wire the shielded twisted pair cable in the minimum distance to the extent possible.
• Ground a shield wire on the encoder side (relay box). Always ground the FG and LG terminals to the protective ground
conductor.
• Do not wire terminals that are not to be used. Doing so may result in malfunction due to noise.
Wiring example for measures to reduce noise
The following figure shows a wiring example of when the measures to reduce noise are reflected to the actual system.
(1)
Keep a distance of 150mm or more from the I/O cables of high voltage devices including a relay and an inverter regardless of whether the devices are
inside and outside the panel.
(2)
For metal pipes, do not use solenoid valves and inductive loads together in a single pipe. When the distance from high voltage cables cannot be kept
because of duct wiring or other factors, use shield wires such as CVVS for the high voltage cables.
(3)
Keep the minimum distance between an encoder and a relay box. When the distance between the flexible high-speed I/O control module and an encoder
is long, a voltage drop may occur. Check that the voltage while the encoder is operating and the voltage while the encoder has stopped are within the
rated voltage range of the encoder using a measuring instrument such as a tester on the terminal block of the relay box. When a voltage drop is large, use
a thicker wire or use the 24DCV encoder that consumes less current.
(4)
Connect the shield wires of the encoder and the shield wires of the shielded twisted pair cable inside the relay box. When the shield wires of the encoder
in use have not been grounded in the encoder, ground them inside the relay box as shown above.
(1)
(2)
(3)
(4)
Terminal block
AC
motor
Relay box
Cart
Encoder
Inverter
Flexible high-speed I/O control module
Programmable controller
To øA
To øB
To the flexible high-speed I/O control module
For the encoder power supply
To +24V
To 0V
To the encoder
Summary of Contents for MELSEC-L Series LD40PD01
Page 2: ......
Page 9: ...7 MEMO ...
Page 24: ...22 2 PART NAMES MEMO ...
Page 35: ...4 PROCEDURES BEFORE OPERATION 33 4 MEMO ...
Page 263: ......