Page 20 - GuardII+ Series 4208 Platform PD User Manual

PD Card Operation

4.4. Synchronization

To properly detect PD activity, it is necessary for GuardII+ to synchronize PD data
collection to the ac fundamental frequency. For BUS and PDA Cards, the synchronization
signal is normally obtained from the sensor, which produces enough residual fundamental
frequency voltage. For SSC Cards, an external source of synchronization is required.
If the synchronization signal becomes ‘noisy’ because of the presence of harmonics or
spikes due to nearby power electronic devices, the GuardII+ may be unable to collect PD
data. In these cases, GuardII+ must be supplied with an alternate external ‘clean’ ac
synchronization signal.
The phase angle difference between the external signal and each phase being monitored
must be known and configured in the monitor.

4.5. Operating Conditions

Measurement results can be affected by the current Operating Conditions of the asset
such as voltage, active power/load, temperature, humidity, etc. Operating Conditions help
when analyzing collected data, but for GuardII+ PD measurements, they are also extensively
used in the data collection algorithms (refer to Section 4.6).

There are three available sources of Operating Condition data:
• Directly from a Modbus slave

• From a Remote I/O Unit (optionally included with the GuardII+)
• From the ambient condition sensor (optionally included with the GuardII+)
The following operating conditions can be measured by the PD monitoring:

Operating Condition Units Acquired Using:
Active Power W, kW, MW, hp Modbus, Remote I/O
Reactive Power var, kvar, Mvar Modbus, Remote I/O
Line Voltage Vac, kVac Modbus, Remote I/O
psi-g, psi-a, kPa-g,
kPa-a, bar-g,
Gas Pressure Modbus, Remote I/O
2
bar-a, kg/cm -g,
kg/cm -a
2
Asset Temperature °C, °F Modbus, Remote I/O
Ambient Temperature °C, °F Modbus, Remote I/O, ambient sensor
Ambient Humidity %R.H. Modbus, Remote I/O, ambient sensor

4.6. PD Measurement Triggers and Archive

The GuardII+ can store up to 2 years of measurement data; this storage is referred to as
the Archive. GuardII+ PD monitoring uses an analysis algorithm to decide when measurement
data should be saved in the Archive. The results of this algorithm are called Triggers.
When a Trigger occurs, measurement data is saved. This includes the entire set of
measurement data; User, Auto and Alert ranges from all enabled inputs. The measurement(s)

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