1.5

Question:

 

Is it possible to load a cable or wire with a voltage class of 300/500 V with a higher voltage for a brief period, provided that the testing voltage value is not exceeded?

 

 

Answer:

Heating systems, for example, require a relatively high voltage to ignite the pilot flame, but this is only needed once or twice a day and for a matter of milliseconds. Operators and users are often of the opinion that a cable with a rated voltage class of, for example, U0/U 300/500 V can be briefly supplied with a higher voltage, provided that it does not exceed the specified testing voltage. In such cases, it is very important to note that a cable with a rated voltage class of 300/500 V and a testing voltage of, for example, 4000 V must never be subjected a voltage exceeding the specified rated voltage – not even for a matter of milliseconds! Even if, for example, a voltage of 2500 V occurs just once per day for a single second, the relevant cable, and the core insulation thickness in particular, must be constructed and tested to ensure the appropriate rated voltage. In this particular case, a cable a with a rated voltage class of 1.8/3 kV must be used to safely handle the briefly occurring voltage of 2500 V.
The testing voltage listed for a specific product on the catalogue page, particularly in the case of ÖLFLEX® connection and control cables, in no way indicates that the relevant cable can be subjected to higher voltages – no matter how briefly.

 

The withstand or high voltage test is a required element of the final acceptance resp. inspection of each and every cable and only serves as a means of identifying any insulation faults after production.