Power transformer additional load losses separation procedure

Abstract

The proposed procedure is based on the fact that total transformer losses (PLL1,n), determined by short circuit test, can be separated into two components: the eddy current losses in the windings (PEC1,n) and stray flux losses (PSL1,n) in iron parts of construction as well as in the transformer tank walls. The total additional load losses, PLLd1 and PLLdh, are determined by short circuit test results, conducted at rated frequency (f1) and at increased harmonic frequency (fh=h*f1). Using so obtained total additional load losses, PLLd1 and PLLdh, which can be expressed in the form PLLdh=PEC1,n*h2 + PSL1,n*h, the corresponding rate additional load losses values PEC1,n and PSL1,n are derived. At the end, for given load with predefined high harmonics content, (Ih/I1n), relative to rated current, the total additional load losses value ΣPLLdh > PLLd1, is found. In such a way all harmonics up to hmax are taken into account.

Keywords

• transformer total losses
• load losses
• additional load losses
• winding eddy-current losses
• stray losses in tank and other parts
• high harmonics losses