Benning ST 755+ - Insulating Resistance

Functions
7.7 Individual tests
5284 / 08/2023 en BENNING ST 755+ / ST 760+ 43
7.7.2 Insulating resistance
EN50678 (VDE0701)
EN50699 (VDE0702)
EN62353
(VDE0751‑1)
EN60974‑4
(VDE0544‑4)
ClassI ClassII ClassIII ClassI ClassII ClassI ClassII
X X X X
(optional)
X
(optional)
X X
By means of this measurement, you can determine whether the insulation of the test sample
has sufficiently high resistances. A high insulating resistance ensures that no fault currents can
flow off [}page80].
The insulating resistance is measured between the following points, depending on the test
standard and protection class:
Test standard Measuring points
R
Insu
-1 LN to PE and conductive accessible parts (ClassI)
LN to test body (ClassII)
Input to test body (ClassIII)
R
Insu
-2 Secondary side to PE and conductive accessible parts (ClassI)
Secondary side to test body (ClassII)
Output to test body (ClassIII)
R
Insu
-3 LN to secondary side (ClassI), (ClassII)
Input to output (ClassIII)
R
Insu
-4 LN to conductive accessible parts without PEconnection (ClassI)
For information devices and components carrying SELV, testing of the insulating resistance
may be dispensed with if damage to the test sample might occur as a result of the
measurement.
According to VDE0751-1, a measurement of the insulating resistance is only necessary for
medical devices if it is considered to be appropriate and is not excluded by the manufacturer's
specifications in the accompanying documents.
The testing current is limited to 1mA for each testing voltage. Tap the “Limits”button to
manually change the applied DCtesting voltage in integers between 100... 500V‑DC (-0%/
+25%) or 501... 1 000V‑DC (-12%/ +25%).
The following testing voltages are preset in compliance with the test standards:
• 250V‑DC
• 500V‑DC
• 1 000V‑DC
Carry out the following additional tests for devices with a secondary output voltage (e.g.
isolating transformers, chargers, converters, power supply units):
1. Insulating resistance measurement between secondary and primary side
2. Insulating resistance measurement between secondary side and the equipment body
3. Contact current measurements of the secondary voltage outputs (except for ClassIII)
4. Measurement of the open-circuit voltage/ output voltage.