What is Class 5 timing accuracy as described in the Sepam Operation manual?

Issue
User needs clarification of what Sepam class 5 timing accuracy is as a percentage

Product Line
Sepam series 20, 40, and 80

Environment
Accuracy specifications

Resolution
Class 5 accuracy is defined in the IEC 60255-151 standard. Class 5 accuracy is ±5%.

This 5% has factors to be considered referring to different parts of the IDMT curve. These factors are defined in part 5.2(Accuracy related to the operate time) table 1 IEC60255-151(2009). This table is provided below.

This table gives the factors for different ranges (Gs= threshold). To determine the real accuracy, multiply the assigned error of 5% by the limiting error from the above table. The assigned error is based on the accuracy class 5 for the Sepam relay. The real accuracy values for each of these ranges is below:

• For current between 2 to 5, real accuracy would be 2.5*5% = 12.5%
• For current between 5 to 10, real accuracy would be 1.5*5% = 7.5%
• For current higher than 10*Gs or 10 times threshold, real accuracy would be 1*5% = 5%

Gepubliceerd voor: Schneider Electric Belgium