Power Supply - ABB TTF200 Operating Instructions Manual

24 TTF200 FIELD-MOUNT TEMPERATURE TRANSMITTER | OI/TTF200-EN REV. B
... 7 Electrical connections
... Electrical data for inputs and outputs

Power supply

Two-wire technology, polarity safe; power supply lines = signal
lines
Note
Following calculations apply for standard applications. This
should be taken into consideration when working with a higher
maximum current.
Input terminal voltage
Non-Ex application:
U = 11 to 42 V DC
S
Ex applications:
U = 11 to 30 V DC
S
Maximum permissible residual ripple for input terminal
voltage
During communication, this is in accordance with the HART® FSK
'Physical Layer' specification.
Undervoltage detection on the transmitter
If the terminal voltage on the transmitter down-scales a value of
10 V, this may lead to an output current of I
Maximum load
R = (U − 11 V) / 0.022 A
B S
A TTF200
B TTF200 in Ex-applications
C HART® communication resistance (R
Figure 22: Maximum load depending on input terminal voltage
Maximum power
• P = U × 0.022 A
s
• Example: U = 24 V  P
s max
≤ 3.6 mA.
a
)
B
= 0.528 W
Voltage drop on the signal line
When connecting the devices, note the voltage drop on the
signal line. The minimum supply voltage on the transmitter must
not be undershot.
+
U
1
-
R
A
A Transmitter
Figure 23: HART load resistance
U : Minimum supply voltage on the transmitter
1min
U : Minimum supply voltage of the supply isolator /
2min
DCS input
R: Line resistance between transmitter and supply isolator
R : Resistance (250 Ω) for HART functionality
250
Standard application with 4 to 20 mA functionality
When connecting these components, observe the following
condition:
U ≤ U - 22 mA × R
1min 2min
Standard application with HART functionality
Adding resistance R increases the minimum supply voltage
250
U : U ≤ U - 22 mA × (R + R
2min 1min 2min
For HART functionality, use supply isolators or DCS input cards
with a HART mark. If this is not possible, a resistance of ≥ 250 Ω
(< 1100 Ω) must be added to the interconnection.
The signal line can be operated with / without grounding. When
establishing a ground connection (minus side), make sure that
only one side of the terminal is connected to the equipotential
bonding.
R
+
250
U
2
-
B
A11122
B Supply isolator / DCS input with
supply / segment coupler
)
250