Decibels (Db); Dc And Ac Currents - Chauvin Arnoux C.A 5011 Manual De Empleo

5 - DECIBELS
Reminder. The measurement of an AC voltage can be expressed
in decibels (symbol dB). The decibel is the ratio of two quantities or
levels. Level N, in dB, of a voltage U has the mathematical expression:
N dB) (
U is the reference voltage of 0.775 V AC for a power P
0
a load of 600 Ω.
Use. Zero level of the red scale in dB corresponds to U
the 4 V AC range. The reading is direct in dB for the 5 V AC range, on
analogue only, from -20 to +16 dB.
The digital display indicates the value of the voltage in volts.
For the other analogue ranges:
500 mV : subtract -20 dB
50 V : add +20 dB
500 V : add +40 dB
1000 V : unusable

6 - DC AND AC CURRENTS

Always switch off the circuit to test before connecting the
multimeter to the circuit. If the "Fus." light comes on, change the
faulty fuse(s) (Reminder: minimum voltage of 100 V).
Connect the leads to the multimeter and connect in series to the
circuit with:
- the red lead in the "µmA", terminal, up to 1 A
- the red lead in the "10 A", terminal, from 1 A to 10 A
When the order of magnitude is not known, place the switch on the
highest range then progressively lower to the appropriate range.
Analogue reading: to get the current in mA, mA or A, multiply the
reading on the appropriate scale by the reading coefficient shown
in the table.
Lecture numérique : si nécessaire, appuyer sur les touches
suivantes
Digital reading: if necessary, press the following keys
~
- for the rms value (See in Ch.3)
- MAX for the maximum value
- HOLD to hold in memory
- for display backlighting
( )
= 20 log U U
10 0
of 1 mΩ on
0
= 0.775 for
0
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