Table of Contents
Advertisement
Available languages
Available languages
2.2.4.2. Measuring the inductance and the quality factor Q in the case of a known measuring range
— With the vernier adjust the pointer deflection to a minimum.
— With potentiometer "Q/D" adjust the quality factor Q so that a better minimum is obtained.
— Repeat this two adjustments alternately for the lowest minimum.
— Ff no clear minimum can be reached, depress push-button "Q" {Q. < 14) and repeat the procedure above.
— When measuring inductances with smaller Q {< 1} various minima can be found by adjustment. The correct
measuring value is obtained at that minimum for which the pointer deflection is the smallest,
— To obtain the exact inductance, multiply the scale reading by the value selected with the range selector
— To obtain the quality factor Q:
When push-button Q js not depressed, the Q is the reciprocal of the loss factor; Q = 4 . Read the loss factor
D on potentiometer "O/D" and multiply by 0.01.
When push-button Q is depressed, the Q can be read directly on potentiometer 'Q/D".
Note: When measuring very high inductances (100 H - 1000 H) the natural resonance frequency can be in
the range of the measuring frequency of the bridge. In this case the measuring result can be considerably
falsed.
Remedy:
If the natural resonance frequency of the inductance can be obtained, the measuring result can be corrected
using the following equation.
fo2 — m2
(x= iM
fo2
Ly = unknown inductance
Lm = inductance measured with the bridge
fo = natural resonance frequency of the coil
f=
measuring frequency of the bridge
(internal 1 KHz or external 100 Hz - 20 kHz)
2.2.5. Measuring with external a.c. voltage supply
If capacitances or inductances are to be measured for measuring frequencies different than internal, an
external sine-wave generator can be connected to sockets "Ext-AC" at the rear of the instrument.
The lower frequency limit of 100 Hz should not be passed because operating the instrument at frequencies
< 100 Hz could cause defects.
For frequencies higher than 20 kHz the bridge sensitivity and thus the measuring accuracy decrease.
The scales for measuring the loss factor D and quatity factor Q only apply for internal measuring frequencies.
For finding these factors at other measuring frequencies the following formulas can be used,
— For capacitance measurement:
Push-button "D" not depressed
iM
1 kHz
Dim = D4 kH2-
Push-button "D" depressed
f
Dim = 0100 Hz Tog
— For inductance measurement:
Push-button "'Q" not depressed
iM
D
pe Bey
1 KHz 7
Dem
=
™
kHz
Of
Advertisement
Table of Contents
