Low Voltage Test
A low voltage test is an electrical test with up to 33 VAC resp. 70 VDC. Typical applications are in their simplest version the open test and the short test. While the open test should validate a set connection between two test points, the short test should detect unwanted connections between individual connections and/or single points. Another option is the functional test, where the functioning of circuits and components is validated by using switching impulses. No special safety circuit is necessarily needed in the low voltage test systems since they provide voltages below 33 VAC resp. 70 VDC, which are—following DIN EN 61010—considered as non-hazardous.
The low voltage test needs to be distinguished from the high voltage test, whose job it is to verify insulation resistance and electric strength (HV-AC test, HV-DC test) resp. measure electric breakdown. Here it is mandatory to fulfill conditions of certain standards that define workplace safety and touchiness.
What is the definition of low voltage, medium voltage, high voltage, and extra high voltage?
Definitions vary somewhat but a general guide to the voltage categories is as follows:
Low Voltage (LV): up to 1000V
Medium Voltage (MV): between 1000 V and 45 kV
High Voltage (HV): between 45 kV and 230 kV
Extra High Voltage (EHV): from 230 kV and above
As a general rule, LV cables might be used in applications like fixed wiring; MV cables are critical power distribution (both for local grid power and for heavy-duty equipment); HV cables are aerial cables – overhead lines for widescale power distribution – often installed on pylons (as are EHV cables).
Some electrical engineers will refer to High Voltage as anything over 1kV, completely skipping Medium Voltage, so if referencing cables be clear on the voltage you are talking about!