Estun E21S, Installation Manual

Page: 38 / 41

Page 38 of 41
Ways to interfere coupling
Ways to interfere coupling are shown in Table 7-1.
Table 7-1
Ways to interfere coupling
Coupling
mode Cause Typical cases
Direct electric
coupling Two or more
circuits use one
guide line Many equipment share one power
supply;
Electrostatic discharge, etc.
Capacity
coupling Capacity coupling
will generate
between any two
conductors. When cables are laid in parallel,
especially when strong and weal
current are in parallel, strong
current will affect weak current.
Inductive
coupling Changing current
flows through
current loop. Transformer;
Contactor and relay pull-in or
disconnect;
High frequency signal cable, etc.
Radio
frequency
coupling Space
electromagnetic
field makes guide
line generate
induced voltage
current.
Measures to ensure electromagnetic compatibility
1. Low resistance grounding: make sure uncharged metal parts (such as enclosure,
shield layer) are ground well. Earth conductor connects to grounding bar inside
cabinet. Grounding bar shall connect the ground by low resistance,
anti-corrosion and make sure good electrical conductivity;
2. Cabling in correct way
−
Cables must be sorted: high-tension line, power line, encoder cable, and
signal line (such as input and output cable).
−
Cables of different kinds shall lay separately and keep distance to the
greatest extent, high-tension line in particular. Do not lay together with
power line, encoder cable and signal line.
−
Encoder cable shall be kept away from power line and signal line to the
largest extent.
3. Connect to shield layer correctly
−
Encoder cable shall have shield layer. Both ends of shield layer must
connect to protective ground.
−
Connected area of shield layer and protective ground shall be as low as
possible. Do not twist the shield layer into a rope. Connect to protective
ground.
−
The smaller resistance between shield layer and protective ground, the
better.
4. Other requirement