RTW SurroundControl 31960 Series, Manual, Page: 221 / 430

EN-5 Safety Instructions | Note about using safety class II compliant external switching power supplies
EN
SurroundControl 31900/31960 Series
Note about using safety class II compliant external switching power supplies
When touching powered-on units with class II compliant ex-
ternal power supplies (e. g. RTW 1178-R, included in 31960
series delivery ) without (correct) audio cabling, extra sensitive
persons might encounter something regarded as electrical
shock. In general, all units shall be connected according to their
respective cabling schemes before bringing them into
service! When accounting for this rule, the described effect
cannot occur.
Nevertheless, we would like to explain it‘s technical background here
Any transformer exhibits not only inductive and resistive, but
also capacitive components and coupling. Via this capaciti-
ve coupling and additional capacitors in the power supply‘s
secondary circuits, a voltage builds up that can be measured
against earth conductor/ground potential. Such voltages, if
measured with a very high-impedance voltage meter, can ea- sily equal or exceed 100 V AC. When connecting audio lines
to units powered by one of the switching power supplies de-
scribed, the measured voltage is discharged over the ground
cabling to the signal common/ground potential. The discharge
current typically will be well below 1 mA.