Surges/Transients; Multichannel Installations; Sensor Connections - Emerson Rosemount 3144P Reference Manual

Reference Manual
00809-0100-4021, Rev AA
March 2002

Surges/Transients

Multichannel
Installations
Figure 2-11. Multichannel
Installations.

Sensor Connections

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) or the Rosemount Model 470 Transient
Protector. 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. The Model 470 transient protector is
available only as an accessory. Refer to the Model 470 Transient Protector
Product Data Sheet (document number 00813-0100-4191) for more
information.
You can connect several transmitters to a single master power supply (see
Figure 2-11). In this case, the system may be grounded only at the negative
power supply terminal. In multichannel installations where several
transmitters depend on one power supply and the loss of all transmitters
would cause operational problems, consider an uninterrupted power supply or
a back-up battery. The diodes shown in Figure 2-11 prevent unwanted
charging or discharging of the back-up battery.
Transmitter
No. 1
Transmitter
No. 2
Figure 2-12 on page 2-16 shows the correct sensor wiring connections to the
transmitter sensor terminals. To ensure an adequate sensor connection,
anchor the sensor lead wires beneath the flat washer on the terminal screw.
Do not remove the transmitter cover in explosive atmospheres when the
circuit is live. Both transmitter covers must be fully engaged to meet
explosion-proof requirements. Use extreme caution when making contact with
the leads and terminals.
R
Lead
Readout or
Controller No. 1
R
Lead
R
Readout or
Lead
Controller No. 2
Between 250 and
1100 Ω If No Load
Resistor
Model 3144P
Battery
Backup
dc
Power
Supply
To Additional
Transmitters
2-15