32
PN: 81127
Rev 4, 6/2017
3.3.1.2
Three or Four SPI Units in Parallel
To parallel the current channels of three or four units, perform the following:
1. Stack the Master unit on top of the Slave units. Interconnect the two slave units together using
the top Slave unit Ethernet port labeled OUT, and connect to the bottom Slave unit Ethernet port
labeled IN (repeat if stacking 4 units). Connect the Master Unit Ethernet port labeled OUT to the
top Slave unit Ethernet port labeled IN.
2. To parallel three or four SPI units together on the 500 Amp output terminals you will need to use
multiple high current cables to connect the output terminals directly to the device under test. It is
recommended that separate test leads be run from each SPI unit directly to the device under test.
Figure 24 - Three SPI Units in Parallel
3. Connect the current outputs to the device under test using properly rated output test leads. If
using test leads other than those supplied by Megger insure that the cable has sufficient size to
carry the test current.
4. Power up all the SPI units within 1 to 2 seconds of each other. The boot-up process will detect
that there are multiple SPI units in a Master/slave configuration.
5. With the STVI (or PC) connected to the Master unit STVI port (or the IN port for a pc), when the
Select Number of Slave Unit menu appears press or click on the number of slave units in use.
6. When the Select a Tap window appears, press or click on 500 Amp tap. The test screen will now
appear.
7. Observe the Connection icon in the upper left hand corner of the screen. You will note that the
number of slave units appears in the Connections icon indicating that you now have control of the
Master and slave units.
8. The software will automatically divide the requested current equally between the connected SPI
units. When setting an output, simply enter the value of the desired output current. For example,
with a three unit stack for an output of 3000 Amperes, enter 3000, and with 3 SPI 500 Amp output
terminals in parallel each unit will be providing 1000 Amperes.
9. See Simple Manual Timing Test for step by step operation
