Download Configuring an Enwatch unit to Piggy-back a Bently Rack

Setting-up the Enwatch unit to “Piggy-Back” a Bently Nevada Rack
Configuring an Enwatch unit to “piggy-back” a Bently Nevada protection system
can provide easy access to real time data and save installation costs on sensors. The
Bently Nevada 3300 and 7200 racks provide buffered output access to non-contact
proximity probe dynamic and static data. These outputs can be wired to the Enwatch
unit for trending and analysis functions. The Enwatch hardware will accept signals from
ICP Accelerometers, AC Coupled and DC Coupled sensors. However, please keep in
mind that the input limitation of each Enwatch channel is restricted to incoming voltage
levels of +/- 10vDC. Commonly, NCPU’s are physically gapped at 50 to 60 mils or 1012vDC electrical GAP. Unfortunately the Enwatch unit will NOT accept voltage inputs
of these levels. For this reason, a “Voltage Attenuator” (EIRD P/N 44826) is used to
lower the GAP voltage below the +/- 10vDC threshold. The calibration value of the
NCPU is affected through this process and should be adjusted in the software
components. This application note illustrates typical Emonitor Odyssey Online setups for
this type input.
The channel used on Enwatch for the NCPU sensor should be set to DC Coupled.
The DC Coupled setting, illustrated below in Figure 1, allows Emonitor Odyssey to
permit trending of both the static GAP voltage measurements and the dynamic AC
components with one Enwatch channel. Using an AC coupled input configuration will
NOT allow you to trend the GAP voltage levels in Emonitor with one channel. A high
pass filter can be used on the dynamic measurements in the Emonitor suite to strip the
DC component. Although the Enwatch hardware is configured for a DC Coupled input
type, the HP filter strips the DC component from the input signal and allows better
utilization of the dynamic range / Analog to Digital converter (ADC) for the AC dynamic
measurements. The Emonitor configuration of this setup will be illustrated later in this
document.
FIGURE 1. Enwatch Hardware Jumper Setting
The wiring of NCPU inputs from the Bently buffered outputs are found below.
The Bently3300 Series racks offer a buffered output from the back plane of the modules
and can be found on the panel terminal strip. Unfortunately the typical Bently 7200
Series racks only offer a buffered output from the Front of the panel. Loading of the
signal can occur if not properly wired. Please consult your Bently Nevada Operators
manual for additional wiring information.
FIGURE 2. Sensor Configuration
In the Emonitor software, the correct measurement configuration must be setup for both
the GAP voltage measurement and the dynamic AC measurements. Figure 3 below
details the typical Emonitor location.
FIGURE 3. Measurement Definition Setup
This measurement location defines two new collection specifications. Figure 4 & 5
defines each collection specification below. The Process Vdc definition has units of
Volts DC (Vdc) and a collection specification called GAP Voltage. The Magnitude and
Spectrum measurements represent the dynamic AC component data setup and are
expressed in units of mils. Figure 4 below illustrates the “GAP Voltage” collection
parameters.
FIGURE 4. GAP Voltage Collection Setup
FIGURE 5. Dynamic AC Measurement Collection Setup
The collection specifications used for this location define new transducers as well.
Figure 6 & 7 below illustrate their respective setup. The calibrations for the transducers
shown below are illustrated in Figure 8. New transducers can be defined by selecting
Setup / Transducer from the main menu of Emonitor.
FIGURE 6. GAP Transducer
FIGURE 7. Dynamic Transducer
The calibration value for each transducer type must be adjusted to compensate for the
“Voltage Attenuator” device wired for the input. Figure 8 below represents the newly
calculated transducer sensitivities given the voltage drop. Both the dynamic and static
transducer are affected.
FIGURE 8. Transducer Calibration Setup
*NOTE: The typical NCPU calibration value can be represented as 200 mV per mil.
The Voltage attenuator divides this voltage by a factor of 2.4. Hence, The new
calibration value is 83.33 mV/ mil. ( 200 / 2.4 = 83.333) The GAP voltage transducer is
affected in a similar fashion. Without a voltage attenuator, any voltage DC input would
have a calibration value of 1000 mV per Volt. Attenuating this by a factor of 2.4 takes
the nominal calibration value to 417 mV/ Volt.
As mentioned above, the attenuator device is used for voltage input levels above
10vDC. If the GAP voltage measurement is below 10vDC an attenuator device may not
be necessary. In which case, all settings mentioned in this document still apply, negating
the calibration values of the transducer. The transducer calibration values would remain
200 mV / mil and 1000 mV / V. As a word of caution however, the attenuator device is
recommended anytime a NCPU input device is used. This avoids any complications in
the event the GAP voltage measurement changes drastically.
The EntekIRD Customer Support Hot-Line can provide further information
regarding the setup of this type measurement. The Customer Support Hot-Line can be
reached by phone at 1-800-368-3547 or via email to [email protected].