User Documentation

28 2661740000/01/06-2020
Measuring
Measuring SPDs
Surge Protective Device (SPDs) in their simplest form comprise one or more non-linear surge protective
components (SPC), a disconnector (thermal or overcurrent) and some form of status indicator (mechanical
or electronic).
The internal surge protective components are generally of two types – voltage switching (GDT, Thyristor
etc.) and voltage limiting (MOV, ABD, TVS etc.). An SPD may also combine such components for example,
a GDT and MOV in series.
An SPD may also have a number of modes of protection, such as Line-Neutral, Line-Line, Neutral-Ground
etc.
Due to these many variations, no one method can be completely outlined for the testing of SPDs. In
general, this requires some understanding and experience on the part of the operator. As a guide:
Step 1 Ensure the status indication of the SPD will not interfere with measurements. If the SPD is a typical
DIN rail type, as used in many IEC based markets, the status indication will be a mechanical ag,
rather than electronic circuit, so isolation of this circuit is not required.
Step 2 Using the manual mode select either GDT or MOV mode based on the components inside the
SPD.
If the SPD is a combination type comprising MOV+GDT it is recommended to manu-
ally set the instrument to its MOV mode by pressing the MOV button. In this mode the
instrument will raise the voltage across the combination type SPD until the switching
component res and a constant current ows through the combination.
The measurement obtained will be a function of the MOV clamp voltage @ 1.0 mA and
the break down voltage of the GDT.
Set the required constant current for the measurement to 1.0 mA (refer to Measurement
screen section).
Step 3 If desired, enable the Log Measurement mode LOG mode (refer to Log screen section). A
check ✔ in the footer panel indicates this mode has been activated.
Step 4 Press the TEST button on the front panel of the instrument. The red high voltage LED will briey
illuminate to indicate that high voltage is being produced at the output terminal sockets (refer to
Safety section).
Step 5 The measured values will be displayed on the output panel.
Compare the measured values with the given table values in the chapter “Surge protection prod-
ucts from Weidmüller”.
The SPD component is defective if the measured value is outside of the minimum to maximum
range given.
For more information on measurement of SPD devices, the user is referred to:
IEC 61643-11 Low-voltage surge protective devices – Part 11: Requirements and test
methods.