ORIGINAL CONTRIBUTION Analysis of Asynchronous Operating Conditions of Synchronous Machines Using Classical and Electromagnetic Models Avik Ghosh 1 • Arabinda Das 2 • Subimal Roy Barman 3 • Amarnath Sanyal 4 Received: 7 May 2019 / Accepted: 20 September 2020 Ó The Institution of Engineers (India) 2020 Abstract Analysis of asynchronous conditions in a syn- chronous machine was initially made by classical method following the generalized machine theory. Later on, it took a turn after the advent of solid iron rotor/solid iron pole- shoe. It was noted that there is a discrepancy between computed and actual quantities between results obtained by the classical and the non-classical model. It was gradually understood that the reason behind this discrepancy was the effect of distributed eddy currents in the solid metallic parts. Authors like B.J. Chalmer, B. Adkins, A. Canay, and others, contributed much to the analysis of asynchronous conditions by adopting new techniques. The paper presents the methodology for using these techniques to estimate the asynchronous variables under loss of excitation (LOE), also to find the same by classical method based on gener- alized machine theory. Keywords Synchronous machine  Asynchronous condition  Solid iron rotor  Solid iron pole-shoe  Distributed eddy current List of symbols r ae ¼ r a þ r e Equivalent resistance of armature, including that of generator bus to grid x ae ¼ x a þ x e Equivalent leakage reactance of armature, including that of generator bus to grid X md ; X mq d-axis and q-axis magnetizing reactance r f ; x f Resistance and leakage reactance of field circuit r kd s  þ jx kd Slip-dependent impedance of the d-axis damper r kq s  þ jx kq Slip-dependent impedance of the q-axis damper s,x, f Slip, angular frequency, frequency L fkd Reactance due to partial linkage between field and d-axis damper X d , X q d-axis synchronous reactance, q-axis synchronous reactance X 0 d d-axis transient reactance X 00 d X 00 q d-axis sub-transient reactance, q-axis sub- transient reactance T 0 do d-axis open-circuit transient time constant T 0 d d-axis short-circuit transient time constant T 00 do d-axis open-circuit sub-transient time constant T 00 d d-axis short-circuit sub-transient time constant T 00 qo q-axis open-circuit sub-transient time constant T 00 q q-axis short-circuit sub-transient time constant X e Armature leakage reactance & Arabinda Das adas_ee_ju@yahoo.com Avik Ghosh avik_be@yahoo.com Subimal Roy Barman roybarmans@gmail.com Amarnath Sanyal ansanyal@yahoo.co.in 1 Electrical Engineering Department, Ideal Institute of Engineering, Kalyani, Nadia, West Bengal, India 2 Electrical Engineering Department, Jadavpur University, KolkataWest Bengal, 700032, India 3 WBSETCL, SLDC, Howrah, West Bengal 711103, India 4 Calcutta Institute of Engineering and Management, 24/1A, ChandiGhosh Road, Kolkata, West Bengal 700004, India 123 J. Inst. Eng. India Ser. B https://doi.org/10.1007/s40031-020-00493-2