Insulating Resistance - Benning ST 755+ Operating Manual

Functions
7.7 Individual tests
7.7.2

Insulating resistance

Class I
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
R -1
Insu
R -2
Insu
R -3
Insu
R -4
Insu
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.
5284 / 08/2023 en
EN 50678 (VDE 0701)
EN 50699 (VDE 0702)
Class II Class III
X
Measuring points
LN to PE and conductive accessible parts (Class I)
LN to test body (Class II)
Input to test body (Class III)
Secondary side to PE and conductive accessible parts (Class I)
Secondary side to test body (Class II)
Output to test body (Class III)
LN to secondary side (Class I), (Class II)
Input to output (Class III)
LN to conductive accessible parts without PE connection (Class I)
BENNING ST 755+ / ST 760+
EN 62353
(VDE 0751‑1)
Class I
X X
(optional) (optional)
EN 60974‑4
(VDE 0544‑4)
Class II Class I
X X
Class II
X
43