Connecting Remote Reset; To 20 Ma Interface Connections; Connecting Cable To The 1900/27 Monitor 4 To 20 Ma Interface - GE Bently Nevada 1900/27 Operation And Maintenance Manual

1900/27 Vibration Monitor Operation and Maintenance Manual

2.5 Connecting Remote Reset

Mounting an external reset switch (or button) at a remote location lets you reset
the monitor without having to open the weatherproof housing. The remote reset
switch can be mounted up to 305 m (1000 ft) from the monitor. Connect the
remote reset switch between the REMOTE RESET A and B contacts. Use a single-
pole single-throw (SPST) type switch with normally open contacts which are
momentarily closed by the switch actuator.

2.6 4 to 20 mA Interface Connections

Systems set up to collect data using a 4 to 20 mA communication system can
access the peak velocity data through this interface. Although the 1900/27
monitor can operate without connecting the 4 to 20 mA interface, the interface
lets you collect data automatically for trending.

2.6.1 Connecting Cable to the 1900/27 Monitor 4 to 20 mA Interface

Use two-conductor shielded cable to connect the 4 to 20 mA loop power supply to
the 1900/27 Monitor. Cable length is restricted by the loop supply voltage, supply
source resistance, and cable impedance. The maximum cable length is determined
by:
where L is the maximum cable length in feet, V
voltage, V is any additional voltage drop in the loop, Rs is the supply source
x
resistance, and Z
(Note that the above equation accounts for the impedance of both the source
and return lines of the cable.)
The following page gives an example for calculating the maximum cable length.
12
is the total cable impedance in ohms/ft.
c
is the minimum loop supply
s