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28.5 VDC Ground Power Unit
Models:
11A6647-1000/1010
11B6647-1000/1010
11C6647-1000/1010
11D6647-1000/1010
11A6647C1000/1010
11B6647C1000/1010
11C6647C1000/1010
11D6647C1000/1010
11A6655-1000/1020
11B6655-1000/1020
11C6655-1000/1020
11A6655C1000/1020
11B6655C1000/1020
11C6655C1000/1020
11D6655C1000/1020
11A6665-1000/1010
11B6665-1000/1010
11C6665-1000/1010
11A6666-1000
11B6666-1000
11C6666-1000
12/2006 - Rev. 04
- 9 -
3.7.1
General (continued)
TRONAIR units have two different kinds of voltage drop compensation available as a standard
feature. One is a remote voltage sensing and regulation system which uses control wires
connected to the + and - pins at the plug. The plug sends it’s voltage signals to the unit’s voltage
compensator controller, which compares them with the voltage readings just prior to the output of
the unit and then automatically adjusts the output voltage accordingly, to overcome the voltage
drop created by the output cables. The second is the I-Boost compensation function. The I-Boost
senses the current flow just prior to the output of the unit and automatically adjusts the output
voltage throughout the full output kW rated range to accommodate the wire characteristics
installed. First an initial installation set up procedure (settings in the software of the unit) has to be
done. (Note: there are limitations as to type of wire and length that can be compensated for). This
I-Boost system uses software and current measurement values to provide the voltage drop
compensation automatically.
3.7.2
I-Boost Compensation
With the I-Boost compensation function, the output voltage of the unit will be modified by a
compensation value, which depends on the output current. If the output current increases, the
output voltage will be increased as well. In this case no additional control wires for the feedback
of the voltage at the load point are necessary. The compensation factor depends on the current,
the type and length of the cable.
In order for the I-Boost function to work correctly, the compensation factor has to be adjusted
initially and whenever the cable construction or length changes. There are two ways of doing the
adjustment. The first requires a resistive load bank, the second way uses the measured reference
values shown in the table below.
Adjustment of the unit using measurements:
One simple measurement is necessary to adjust the I-Boost function. The measurement is done
with a resistive load.
Measurement:
•
Disable the remote sensing and the compensation at the setup menu
•
Connect the resistive load, turn on the Output voltage and apply the “Full Load”
•
Measure the voltage at the plug while the converter supplies the nominal output voltage
•
Calculate the difference between the average measured voltage and the nominal voltage
•
With the load disabled and the Output off, enter the average value (rounded to the nearest
whole digit) into the Setup-Menu “Compensation” – “Active Power”
•
Enable the compensation mode
•
Turn on the output voltage, enable the “Full Load” and repeat the measurement
•
With the load disabled and Output power off, add any additional difference to the adjusted
value in the “Compensation” – “Active Power” entry
If it is not possible to make the measurement at nominal load, the correct value for the adjustment
can be calculated using the following formula:
Example: Nominal active power - 16kW; actual active power - 8kW, measured difference values
is: Udiff=2,5V
•
The calculation of the value for the adjustment is: 2,5V x 16kW/8kW=5.00V
•
The value for the adjustment is: 5V
3.7.2 I-Boost compensation continued on following page.