Argantix XDS 100-100, User And Programming Manual

Page: 57 / 116

User and Programming Manual
XDS Series 57
7.3.3 Current Sharing Calibration on Multi-box Systems
Systems consisting of multiple XDS units in parallel may require periodic checking and adjustment of
the current sharing. If a system was shipped configured from the factory, the current sharing was set
at the time of shipment. Systems that are configured in the field using XDS units that were not
originally factory configured as such, must be be checked and adjusted as needed. This section
covers the required adjustment procedure.
This test makes adjustments to all Auxiliary power sources used in a multi-box power system. The
test is done with the assumption that all measurement calibrations have been performed on all power
sources used in the system. The load for the parallel power system must be derived from Table 7-2.
In order to derive the resistance needed for the load find the load resistance value for a 15 KW
OUTPUT. Multiply this value by the factor 15/(total power in KW). This value will be the full-load
resistance value.
For example if the power system has an 80 volt range and the total system power level is 25 KW the
full-load resistance is: (15/ 25) X 0.427 = 0.256 ohms.
Proceed as follows:
1. Connect the analog cable, 5005-051-1, between the Master power source and each Auxiliary
power pin11 source. J21 of the Master must connect to J22 of the Auxiliary Source. J21 pin 2
of the Master source must connect to J22 pin 14 of each Auxiliary source. J21 pin6 of the
Master source must connect to J22 of each Auxiliary source.
2. Configure the auxiliary unit’s controller if it is not already set for –AUX configuration. In each
Auxiliary power source remove jumper W12 and install jumper W13 and W14 on the 5005-
720 controller board. Note, if the intended –AUX unit has a P/N 5005-708-1 controller board,
it does not support parallel operation.
3. If the total system power is 45 KW or more install jumper W15 on the Master Controller
board. W16 should already be installed.
4. Connect the outputs of all of the power sources in parallel. Use adequate wire sizes. Connect
a suitable current shunt in series with each unit so the current delivered by each unit can be
monitored individually. If suitable current shunts are not available, the internal current read
back of the XDS units may be used instead provided the current measurement calibration of
each XDS unit has been verified beforehand.
5. Apply the full-load resistance value derived above. Make sure the load is rated for the power
level that will be dissipated.
6. Turn on the line power first for the Master power source followed by each Auxiliary source.
7. Apply the output of each Auxiliary source followed by the Master source. Make sure that the
output voltage stays at a low value, less than 0.5% of full-scale voltage, after each Auxiliary
source has the output applied.
8. Note: If the Master and Auxiliary power sources are not of the same model (same number of
amplifiers) a constant , R, must be determined for the full-scale current tracking of the
Auxiliary power source. R = (Auxiliary maximum current)/ (Master maximum current) For
most power systems the model number of the Master and Auxiliary will be the same to the
value of R will be equal to 1. This would mean the current delivered by the sources should be
the same.
9. The full-load current from each Auxiliary source should match the full-load current delivered
by the Master within 5%. The current delivered by each Auxiliary source must match the
current delivered by the Master times the constant R. For example if the constant is 2/3 when
the Master is delivering 100 amps the Auxiliary with the constant R should be delivering
66.66 amps. In order to make this adjustment slowly increase the output voltage of the
Master source while observing the load current supplied by each Auxiliary source. The