Voltech AT5600, Руководство пользователя

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C H A P T E R 1 3 – T E S T F I X T U R E S
AT5600 User Manual 98-119 issue 14
Page 268
13.6. General Notes
The following general notes should be considered when constructing or modifying
fixtures.
13.6.1. Beware of High Voltages
The AT5600 can apply DC voltages up to 7000 V DC and AC voltages up to 5000
V AC during a test. This must be kept in mind when constructing test fixtures.
If possible, always design the fixture with the nodes that experience the same
high voltages grouped together.
An example of this is the common situation of performing Hi-pot tests between the
primary windings as a group, and the secondary windings as a group.
The best layout for the test pins in this case (assuming this is not prohibited for
other reasons) is to have all the primary windings connected to test nodes on one
side of the fixture board (say the left-hand side using nodes 1, 3, 5, 7, etc.), and to
have all the secondary windings connected to test nodes on the opposite side (for
example, nodes 2, 4 and 6).
If, in addition, you need to test the isolation between two secondary windings, use
the low-numbered nodes (say 2, 4 and 6) for one winding and a well separated
group of high-numbered nodes (say 14, 16 and 18) for the other.
For PCB mounting transformers, clearly the spacing between the pins is
determined by the transformer itself. If necessary, place pieces of high-voltage
insulation between each Kelvin blade and its nearest neighbors, to prevent any
high voltage flashover.
When separate terminals are used for transformers with flying leads, you should
ensure that there is a generous separation between individual terminals to allow
for the high voltages in your program. Consider both the exposed (high-voltage)
metal parts of the terminal itself, and the free ends of the transformer lead, which
may be carelessly inserted and may bend around to touch an adjacent terminal.
Ensure that there is a separation of at least 3 mm per kV between any sharp
points in an air gap, assuming that the air is dry. Increase the separation still
further for conditions of high humidity.
All leads between the terminals, or crocodile clips, and the contact pins on the
AT5600 fixture plate should be covered with insulation capable of withstanding
the test voltages you are using in your programs. They should be kept as short as
possible, and the leads from one power-sense pair should not touch any bare
metal associated with another power-sense pair.
Terminals or interconnections, which have exposed (high voltage) metal in
contact with the surface of the fixture board, should be avoided where possible,
as there may be creepage along the surface. If such a terminal is necessary, you
must ensure that there are no sharp points or corners on the metal pieces, that