Yokogawa YTA320 - Manual (Page 24)

<5. Wiring>
5-
IM 01C50B01-01E
5. Wiring
5. Notes on Wiring
IMPORTANT
• Apply a waterproofing sealant to the threads
of the connection port. (It is recommended
that you use non-hardening sealant made of
silicon resin for waterproofing.)
• Lay wiring as far away as possible from
electrical noise sources such as large
transformers, motors and power supplies.
• Remove the wiring connection dust-caps
before wiring.
• To prevent electrical noise, the signal cable
and the power cable must not be housed in
the same conduit.
• The terminal box cover is locked by an Allen
head bolt (a shrouding bolt) on ATEX, IECEx
and TIIS flameproof type transmitters.
When the shrouding bolt is driven clockwise
by an Allen wrench, it is going in and cover
lock is released, and then the cove can
be opened by hands. See Subsection 6.3
“Disassembly and Reassembly” for details.
5.2 Loop Construction
The YTA is a two-wire temperature transmitter that
uses the output power supply wiring and signal
wiring alternately.
The transmission loop requires DC power. Connect
the transmitter with the distributor as shown in
Figure 5.1 or Figure 5.2.
For the transmission loop, the load resistance of
the distributor or other instrument to be installed in
the loop and the lead wire must be within the range
shown in Figure 5.3.
For details of communication requirements, refer to
the additional reference materials, IM 01C50T03-
01E “YTA Series BRAIN Communication”,
and IM 01C50T01-01E “YTA Series HART
Communication”.
F0501.ai
<Hazardous location> <Nonhazardous location>
+
Output signal
–
Distributor
(power supply unit) Receiver
Input signal
(thermocouple,
RTD, mV, etc.)
Figure 5. Loop Construction (for General-use
Type and Flameproof Type)
F0502.ai
<Hazardous location> <Nonhazardous location>
+ Output signal
–
Distributor
(power supply unit) Receiver
Safety
barrier
Input signal
(thermocouple,
RTD, mV, etc.)
Figure 5.2 Loop Construction (for Intrinsically
Safe Type)
600
250
10.5 16.4 24.7 42
Power supply voltage E (V DC)
R= 0.0236
E–10.5
F0503.ai
External
load
resistance
R
(Ω)
Communication
applicable range
BRAIN and HART
Figure 5.3 Relation between Power Supply
Voltage and Load Resistance
Note: For intrinsic safe explosion-proof type units, the internal
resistance of the safety barrier is also included in the load
resistance.
5.3 Cable Selection
5.3. Input signal Cable Selection
A dedicated cable is used for connection between
the temperature sensor and the temperature
transmitter.