BRUEL & KJAER 2663, Technical Documentation Manual

Page: 17 / 54

Chapter 2 — Operation
Output and Supply Connections
Preamplifiers Types 2663 and 2663 B
User Manual
Brüel & Kjær
10
Fig.2.5 Connection of differential accelerometer to Type 2663/2663 B using double-screened, two-
core, low-noise, accelerometer cable
Since the shield of the accelerometer output socket is part of the accelerometer
housing which is grounded by the vibration test-specimen, it is essential that the
outer-cable screen is not connected to the inner-cable screen or the outer shield of
the preamplifier input-socket.
Isolation
In some circumstances, particularly when using ready-made cables, it may not be
possible to avoid interconnecting the outer shield of the accelerometer output and
preamplifier input with the cable screen. A simple solution to this problem, which
may be employed when relatively short input cables are used, is to isolate the accel-
erometer from ground by using an isolating stud and mica washer for mounting. If
this is not possible, then disconnect the grounded/floating connection on the pream-
plifier circuit.
2.4 Output and Supply Connections
The output connector of the preamplifiers is a 6-pin bayonet socket. It contains two
pins for the power input to the preamplifier, as well as signal output, overload and
signal ground pins. The pin designations are shown in
Fig.2.6 . Included in the acces-
sories is a 6-pin, Cannon-plug connector (Brüel & Kjær Type JJ 0615 or JJ 0624) which
is described in
section 4.1 .
Fig.2.6 Type 2663/2663 B output socket (external view)
Input
Vibration Test Specimen
Preamplifier
2663
Differential
Accelerometer
grounded by
vibration test
specimen
E
D
B
C
A
F
890749e
890751e
V
V
Overload
DC out
AC out
Signal
Ground
A
F
E
B
C
D
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