Start-Up Procedure - BRUEL & KJAER System V Instruction Manual

Head, a push rod is generally used to transfer the force. This can also be used to provide
3 . 11
externai protection for the Head. The dimensions and stiffness of the rod should be de-
signed in such away that side loads and moments result in bending of the rod rather
than rubbing of the side load pads.
5 mm Steel Rod Si lver Solder
10·32 UNF
/
I
~
e
(]}
M 3 Screws
(al
/ Hose Clam p
A lum in iu m T ube
,(t):E
~
10·32 UNF
Slot
Fig. 3.7.
(bl
271 401
Push rads for use with the Mode Study Head
3.1
3 .1
Fig .3 .7 shows sketches of two types of push rods for use with the Type 4814 Head . In
a) the two halves are screwed tight to the Exciter Head and the object, then locked to ­
gether by means of the four centre screws . In b) a slotted aluminum tube is slipped over
the two 10 - 32 UNF screws , then clamped in place with small hose clamps. This is
only suitable for applications at frequencies below 500 Hz .
3.10. START-UP PROCEDURE
This section assumes the Exciter system is powered by the 2707 Power Amplifier driven
by a suitable signal source. Before the Exciter is turned on, all actions discussed in sec­
tions 3 . 1 to 3.8 should have been completed. Set the CURRENT LIMIT and DISPLACE­
MENT LIMIT controls according to the characteristics of the Head employed . For the
4805 without cooling, the CURRENT LIMIT on the power amplifier should be set to half
the value stated on the Head . The AMPLIFlER GAIN controi should be in its " Reset" posi­
tion . EXCITER INTERLOCK should be "In".
3 .1
To turn on the Exciter, turn the POWER switch on the Power Amplifier clockwise to
" Power On", and after a one second pause, further clockwise to "Load On ". The " Power
On" position turns on the power supplies in the Power Amplifier and the Field Supply
and Blower Motor in the Exciter Body Type 4801 . The "Load On " position conn ects the
driver coil of the Exciter Head. The one-second pause prevents starting-transients from
causing motions of the moving element.
3.
Confirm that the signal source connected to the input to the Power Amplifier is correctly
adjusted .
Turn the AMPLIFlER GAIN controi from the " Res et" position slowly clockwise until the
desired amplitude of vibration is reached . A counter -clockwise turn and click to the
"Reset" position resets the protective circuits and connects the signal source to the
Power Amplifier if some abnorma I use has tripped off one of the protective circuits .
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