Title :
On the protection of thermal processes
Author :
Zocholl, Stanley E. ; Benmouyal, Gabriel
Author_Institution :
Schweitzer Eng. Labs., Holland, PA, USA
fDate :
4/1/2005 12:00:00 AM
Abstract :
Standards specify an equation for the time-current characteristic of a thermal relay. When the equation is published without reference to its derivation, it may be mistaken for the characteristic of an inverse-time overcurrent relay which if implemented would provide only marginal protection. This paper explains the ambiguity introduced in the standard and addresses thermal protection from the perspective of a thermal model that provides optimum protection. The paper employs MATLAB simulations to compare the dynamics of the thermal model with that of an overcurrent implementation during cyclic overloads.
Keywords :
mathematics computing; overcurrent protection; relay protection; thermal engineering; MATLAB simulations; cyclic overloads; optimum protection; overcurrent protection; relay protection; thermal model; thermal protection; thermal relay; time-current characteristic equation; Conductors; Differential equations; IEC standards; MATLAB; Mathematical model; Protection; Protective relaying; Relays; Temperature; Thermal resistance; Digital relaying; inverse-time characteristic; motor protection; overcurrent protection; overcurrent relays; thermal protection; thermal relays; time-current characteristic;
Journal_Title :
Power Delivery, IEEE Transactions on
DOI :
10.1109/TPWRD.2004.841304