LS Industrial Systems GLOFA G7M-DR20U, User Manual

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Chapter 7. Usage of Various Functions
7-74
4-wire
type
No wiring
*1 : Pt
*2: Shield wire
9) Wiring
(1) Caution for wiring
•
Make sure that external input signal of the mixture module of AC and analog I/O is not affected by induction noise or occurs
from the AC through using another cable.
•
Wire is adopted with consideration about peripheral temperature and electric current allowance. Thicker than Max. size of
wire AWG22 (0.3
㎟
) is better.
•
If wire is put near to high temp. radiated device or contacted with oil for a long time, it may cause of electric leakage so that it
gets broken or miss-operation during wiring.
•
Be sure to connect with care of polarity while connecting to external 24V DC power supply.
•
In case of wiring with high voltage line or generation line, it makes induction failure so then it may cause of miss-operation
and out of order.
(2) Wiring example
•
Number of method of connection between Pt and RTD input module are three, that is, 2-wired type, 3-wired type and 4-w
wired type.
•
The resistance of the wires used to connect Pt to RTD input module should be 10
Ω
or less per wire.
The same wire (in thickness, length, and kind, etc.) should be used for each channel.
Connection
Method
Connection Example Wire Conditions
2-wired type
3-wired type
ℵ
wire resistance
≤
10
Ω
ℑ
wire resistance
≤
10
Ω
ℜ
wire resistance
≤
10
Ω
The difference between the resistance values
of the wires
①
and
②
: 1
Ω
or less
The difference between the resistance values
of the wires
②
and
③
: 1
Ω
or less
The difference between the resistance values
of the wires
③
and
①
: 1
Ω
or less
burn-out detection