Location of Vibration Transducer Adapters, T53-L-3/7 Engines

1-39. CALCULATION OF CORRECTED SENSI-

TIVITY. The sensitivity rating, S, can only be assumed

correct when given in terms of operation into a load

impedance equal to the input impedance of the vibra-

1-38. VIBRATION TRANSDUCER SENSITIVITY RAT-

tion meter used. The input impedance of Vibration

ING. The basic sensitivity rating of velocity respon-

Meter Type 1-117-0105 is 10K ohms, and all Consoli-

sive vibration transducers is given by the following

dated Electrodynamics Corp. vibration transducers

formula:

are rated in terms of operation into a 10K + 500 ohm

load. If vibration transducers rated for load imped-

where:

ances other than 10K ohms are used, it is necessary

to calculate the "corrected sensitivity."

S = the sensitivity rating, expressed as

"millivolts per inch per second"

a. Sample calculation when vibration transducer

E = millivolts, i.e., (volts divided by 1000)

open-circuit voltage is known (see figure 1-22):

V = velocity in inches per second

Sample No. 1: With S1 known to be 62 millivolts

The sensitivity rating, S, is given in consistent units,

per inch per second and R1 known to be 925 ohms,

i.e., if the input velocity is given in average inches/

and using equation

corrected

second, it may be multiplied by S to obtain average

millivolts output; if the input is given in RMS inches/

sensitivity, the following sample calculation is given:

second, it may be multiplied by S to obtain RMS

millivolts output, etc.