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3.4. CURRENT LIMIT TIME CONSTANT
The
averag,
i ng time constant of the CURRENT protection circuitry can
be reduced from the nominal 50 seconds to 2.5 seconds by removing the
shorting link between the terminal pins on Card ZL 0028 (Fig.3.9).
Remove shorting
link for 2.5 sec.
current averaging
time
271
0
<(
8
Fig.3.9. Shorting link to increase CURRENT averaging time constant
3.5. MULTIPLE EXCITER VIBRATION TESTING
Certain vibration applications require more than one Exciter to drive the
test specimen. This type of connection is shown in the schematic diagram of
Fig.3.10 .
.
To provide complete protection, a trip in any one Amplifier-
Exciter combination must remove the input signal from all Amplifier-
Exciter pairs in use. This is accomplished using the ACCESSORY sockets of
the 2707s.
Select one of the Amplifiers as the Master and the remainder as Slaves.
Remove the shorting link between pins
4
and 5 on all the Slave amplifiers
and, using external connectors and wiring, link pin 5 of each amplifier to
pin 5 of every other amplifier.
The FET gates at the input to each amplifier are now parallelled and the
gates' "on" bias is supplied from the Master Amplifier.
22
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