Surges/Transients; Grounding - Emerson Rosemount 3144P Reference Manual

Reference Manual
00809-0100-4021, Rev EA
March 2007
Figure 2-13. Load Limits.

Surges/Transients

Grounding

NOTE
Do not allow the voltage to drop below 12.0 V dc at the transmitter terminals
when changing transmitter configuration parameters, or permanent damage
to the transmitter could result.
Maximum Load = 40.8 X (Supply Voltage - 12.0)
F fieldbus
OUNDATION
Powered over F
OUNDATION
The transmitter operates between 9.0 and 32.0 V dc, 11 mA maximum.
Transmitter power terminals are rated to 42.4 VDC.
The power terminals on the 3144P with F
insensitive.
The transmitter will withstand electrical transients of the energy level usually
encountered in static discharges or induced switching. However, high-energy
transients, such as those induced in wiring from nearby lightning strikes, can
damage both the transmitter and the sensor.
To protect against high-energy transients, install the integral transient
protection board (option code T1). The integral transient protection board is
available as an ordered option or as an accessory. Refer to " Transient
Protection (Option Code T1)" on page A-16 for more information.
Sensor Shielding
The currents in the leads induced by electromagnetic interference can be
reduced by shielding. Shielding carries the current to ground and away from
the leads and electronics. If the ends of the shields are adequately grounded,
little current will actually enter the transmitter.
If the ends of the shield are left ungrounded, a voltage is created between the
shield and the transmitter housing and also between the shield and earth at
the element end. The transmitter may not be able to compensate for this
voltage, causing it to lose communication and/or go into alarm. Instead of the
shield carrying the currents away from the transmitter, the currents will now
flow through the sensor leads into the transmitter circuitry where they will
interfere with the circuit operation.
Rosemount 3144P
4–20 mA dc
1240
1100
1000
750
500
Operating
Region
250
0
10 20 30
12.0
Supply Voltage (V dc)
fieldbus with standard fieldbus power supplies.
OUNDATION
40 42.4
fieldbus are polarity
2-15