8.7 Protective conductor resistance (R
PE
)
Resistance between any conductive touchable parts, connected to the
protective conductor for protective purposes, and the earthed contact of the
mains plug, the device plug or the protective conductor, which is constantly
connected to the mains power supply.
During the measurement of the protective conductor resistance, the connecting
cable should be moved, section by section, along its whole length. This
measuring method only applies for devices of protection class I.
Also see measuring principle circuit M1 on Page 17.
8.8 Visual inspection
Testing in accordance with DIN VDE 0701-0702 also requires visual
inspection of the device.
According to the standard, the devices should be inspected for external
defects (without opening the device) and, as far as possible, for suitability to
the place of installation. In particular, attention should be paid to the
following:
– Damage to the housing
– Defects of the cord connector guard and strain relief fittings
– External damage of the connecting cables
– Unauthorised interference and changes
– Signs of overloading and improper use
– Orderly condition of the protective covers
– Safety impairing soiling and corrosion
– Unblocked cooling vents
– Existence of necessary air filters
– Leak tightness, pressure relief valve
– Legibility of safety-related inscriptions
– Fuse links in accordance with manufacturer’s specifications
Externally visible defects, which could lead to a mechanical
or fire hazard should be repaired immediately.
16
Operating manual for the TG uni 1, TG euro 1 and TG euro 1 med appliance tester
Explanation of terminology
8.5.2 Devices without a protective earth connector (PC II)
The active parts are separated by strengthened or double insulation (basic
insulation and additional insulation). This ensures protection against direct
contact.
Protection against indirect contact is also given, since an insulation fault is
practically impossible. Such devices can nevertheless have touchable
metallic housing parts. Devices of protection class II have a mains plug
without an earth contact.
8.5.3 Devices connected to protective extra-low voltage electric
circuits (PC III)
Devices of protection class III are exclusively connected to protective extra-
low voltage electric circuits - SELV / PELV.
The protection against dangerous body currents is achieved by the low
voltage and the safe separation from other electric circuits.
8.6 Protective conductor current (I
PE
)
Current that flows through the protective conductor of protection class I
devices (test objects) when their bodies are insulated from earth.
A direct measurement is applicable if the test object can be insulated from
earth.
In all other cases the differential current method should be applied, see Point
6.3 (Basic settings of the tester, Page 10).
Also see measuring principle circuits on Page 18.
Caution! The test object is supplied with mains voltage
during the test.
