Agilent Technologies E6198B, Руководство пользователя

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5-10 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 J3 together and one that ties all the pins on
J4 together. The NO pins are jumpered to power bus 2, and the
NC pins are jumpered to power bus 1. The jumper combs for J3
and J4 can be easily cut to provide bus or pin isolation between
the various input/power bus connections. For example, if you
use one of the channel pairs in a bridge configuration, you
would probably disconnect that channel from the J4 jumper
comb to eliminate possible power bus interaction.
Selecting a Current-Sense Method
There are two ways to measure current on the Agilent E6175A
8-Channel Load Card; using a sense resistor, or using a LA
25-NP current transducer from LEM Inc.
*
Figure 5-5 shows the
relationship between the sense resistor (Rs) and the LEM
module current transducer (only one or the other is used, never
both).
Sense Resistors
The card comes factory loaded with a 3-watt, 0.05
Ω
, 0.1% sense
resistor already installed. This is the lowest value sense resistor
that can safely be installed. If lower value currents are being
measured, requiring a larger resistance value to make the sense
voltage readable, then this sense resistor can be replaced by a
four-wire resistor of higher value. The sense resistor should
suffice for most measurements except those that require that
the measurement be isolated from high common-mode voltage
transients.
Current Transducers
The load card is designed to accept a LEM current transducer
(LEM module) to be inserted in the circuit in place of the
current-sense resistor.
* This module was tested with a LEM Model LA25-NP Current Transducer from LEM USA, Inc. 6643 West
Mill Road, Milwaukee, WI, 53218. (414) 353-0711