Touch current check
(After completing the work, measure touch current to prevent an electric shock.)
-)Plug the AC cord directly into the AC outlet. Do not use an isolation transformer for this check..
-)Connect a measuring network for touch currents between each exposed metallic part on the set and a good earth
ground such as a water pipe, as shown in Figure D.1
-)The potential at any point(TOUCH CURRENT) expressed as voltage U1 and U2 does not exceed the following value:
The part or contact of a TERMINAL is not HAZARDOUS LIVE if:
a) the open-circuit voltage does not exceed 35 V (peak) a.c or 60 V d.c.,
or,if a)is not met,
b) the measurement of the TOUCH-CURRENT shall be carried out in accordance with IEC 60990, with the measuring network
described in annex D of this standard.
The TOUCH CURRENT expressed as voltages U1 and U2, does not exceed the following values:
- for a.c.:U1= 35 V(peak)and U2=0.35 V (perk);
- for d.c.:U1= 1,0 V,
NOTE 5 -The limit values of U2=0.35 V (peak) for a.c. and U1=1.0 V for d.c. correspond, to the values 0,7mA (peak) a.c. and 2,0
mA 2,0mA d.c.
The limit value U1= 35 V (peak) for a.c. corresponds to the value 70mA (peak) a.c. for frequencies greater than 100 kHz.
Annex D
(normative)
Measuring network for TOUCH CURRENTS
Rs=Cs=
A1 500á0.22uF
Test TERMINALS10ká
B
Rb=
500á
U10.022uFVU2(V)
IEC 802/96
Resistance values in ohms(�)
V: Voltmeter or oscilloscope
(r.m.s or peak reading)
Input resistance: �ë1 M�
Input capacitance: 200 pF
Frequency range: 15 Hz to 1 MHz and d.c. respectively
NOTE-Appropriate measures should be taken to obtain the correct value in case of non-sinusoidal waveforms.
The measuring instrument is calibrated by comparing the frequency factor of U2 with the solid line in figure F.2 of
IEC 60990 at various frequencies. A calibration curve is constructed showing the deviation of U2 from the ideal
curve as a function of frequency.
TOUCH CURRENT=U2/500(peak value)
Fig.D.1 |
ACEC
TOSHIBA
