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Grounding Considerations
When using the exciter in complex measurement setups, indiscriminate grounding of
the instrument signal ground lines may introduce mains hum. This can be avoided
by ensuring that the signal ground line of the entire measurement setup is grounded
at one point only. To do this without prejudicing the operating safety of the instru-
ments involved:
1) Connect the signal ground lines of all instruments together. This is done auto-
matically through the screens of the input and output cables used to intercon-
nect the instruments.
2) If instruments equipped with a mains socket chassis terminal are employed in
the measurement arrangement then check that: a) one and only one of these
instruments has its signal ground line connected via chassis to mains ground, b)
the housing of the measurement transducer is isolated from grounded measure-
ment sources.
3) If the measurement arrangement is free-standing without instrument cabinets
touching, then ensure that each of the other instruments in the measurement
arrangement has its chassis connected to mains ground only or chassis only.
Mains ground is preferred for instruments with a mains socket chassis terminal.
Operating Procedure
After making the system checks and connections described in "System Checks and
Connections", please consult instructions for operation of Signal Generator and Pow-
er Amplifier before commencing operation.
Mounting and Use of Modal Exciters Types
4825 and 4826
Modal Exciters Types 4825 and 4826 can be used in any position and angle relative
to the structure under test. Mounted in its trunnion, the exciter can be placed di-
rectly on the floor. Some applications, such as when the exciter is suspended at
some height from ground – and used laterally, horizontally or at a skewed angle –
may require use of dedicated suspension techniques. For convenient lateral excita-
tion up to a height of 2 meters, Lateral Modal Exciter Stands UA 1607 and UA 1608
are available.
The "hole-through" design makes it possible to use tension wire stingers or tradi-
tional push/pull stingers with the exciter. Easy and fast attachment of both types of
stingers is achieved with the chuck nut assembly or with an M6 to 10–32 UNF
threaded insert.
CHAPTER 2
7
Operation
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