5-28 E6198B Switch/Load Unit User Manual
5 Using Load Cards and Loads
The factory default is to provide two jumper combs, one that
ties all the pins on J4-J7 (NO) together and one that ties all the
pins on J8-J11 (NC) together. The NO pins are jumpered to
power bus 2, and the NC pins are jumpered to power bus 1. The
jumper combs for J4-Jll can be easily cut to provide bus or pin
isolation between the various input/power bus connections.
Selecting a Current-Sense Resistor Value
The card comes factory loaded with a three watt, 0.05Ω, 0.1%
sense resistor already installed. This is the lowest value sense
resistor that can be installed safely. If lower value currents are
being measured, requiring a larger resistance value to make the
sense voltage readable, then replace the sense resistor with a
four wire resistor of higher value.
Selecting a Load Fuse
The load fuses used are IEC 5x20 millimeter, 5-amp slow-blow.
These fuses may be replaced by fuses with a higher value, but
not to exceed 8 amps.
Selecting and Loading Flyback Protection
Coils used as loads may have large flyback voltages which have
the potential to damage other electronic components. Generally
the UUTs are equipped with flyback protection, so flyback
protection on the load cards is redundant but provides backup
protection in case a defective UUT is tested. The system
integrator is responsible for ensuring the flyback protection
devices are installed on the load cards.
The maximum fuse rating must not exceed an I
2
T value of
102-126.
*
* The I
2
T figure is an industry standard term. For example, if a fuse with a rating of I
2
T =
100 experiences a current surge of 10A, it can maintain that current for 1 second before its
capacity is exceeded. (10A * 10A * 1 Second = 100)
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