EMF Equation of a Synchronous Generator

Edwiin
05/27/2025

Synchronous Generator and EMF Equation Derivation
A generator operating at synchronous speed is termed a synchronous generator, which converts mechanical power into electrical energy for grid integration. The derivation of the EMF equation for a synchronous generator is as follows:
Notation:
  • P = number of poles
  • ϕ = flux per pole (Weber)
  • N = rotational speed (revolutions per minute, r.p.m)
  • f = frequency (Hertz)
  • Zph = number of series-connected conductors per phase
  • Tph = number of series-connected turns per phase
  • Kc = coil span factor
  • Kd = distribution factor
Derivation: The flux cut by each conductor in one revolution is Pϕ Weber. The time to complete one revolution is 60​/N seconds. The average EMF induced per conductor is given by:
Average EMF induced per phase will be given by the equation shown below:
Average EMF Equation Assumptions
The derivation of the average EMF equation is based on the following assumptions:
  • Coils exhibit full pitch configuration.
  • All conductors are concentrated within a single stator slot.
The root mean square (RMS) value of the induced EMF per phase is expressed as:Eph = Average Value×Form Factor Thus,
EMF Equation and Winding Factors
Equation (1) above represents the EMF equation of a synchronous generator.
Coil Span Factor (Kc)
The coil span factor is defined as the ratio of the induced EMF in a short-pitched coil to that in an identical full-pitched coil.
Distribution Factor (Kd)
The distribution factor is the ratio of the induced EMF in a distributed coil group (wound across multiple slots) to that in a concentrated coil group (wound in a single slot).
Edwiin

Hello,I'm Wdwiin. A decade of hands-on experience in electrical engineering, specializing in high-voltage systems, smart grids, and renewable energy technologies. Passionate about technical exchange and knowledge sharing, committed to interpreting industry trends with professional insights to empower peers. Connection creates value—let’s explore the boundless possibilities of the electrical world together!

Cost Differences and Performance Comparison of 35kV New Energy Transformers Based on Dry-Type, Mineral Oil, and Vegetable Oil
Cost Differences and Performance Comparison of 35kV New Energy Transformers Based on Dry-Type, Mineral Oil, and Vegetable Oil
For users, when purchasing a 35kV new energy transformer, choosing between dry-type, mineral oil-filled, or vegetable oil-filled types involves multiple considerations. These include user habits, maintenance-free performance, safety and fire resistance, volume and weight, among others. However, cost differences are undoubtedly one of the most crucial factors.To illustrate the issue intuitively, this paper selects a three-level energy efficiency dual-winding new energy transformer with a rated ca
Ron
07/26/2025
What is the connection group of a transformer?
What is the connection group of a transformer?
Transformer Connection GroupThe connection group of a transformer refers to the phase difference between the primary and secondary voltages or currents. It is determined by the winding directions of the primary and secondary coils, the labeling of their start and end terminals, and the connection mode. Expressed in a clock-like format, there are 12 groups in total, numbered from 0 to 11.The DC method is commonly used to measure the transformer's connection group, mainly to verify whether the con
Vziman
07/26/2025
What is the sequence for powering down the transformer?
What is the sequence for powering down the transformer?
The sequence for shutting down a main transformer is as follows: when de-energizing, the load side should be shut down first, followed by the power supply side. For energizing operations, the reverse order applies: the power supply side is energized first, then the load side. This is because: Energizing from the power supply side to the load side makes it easier to identify the fault range and take prompt judgment and handling measures in case of a fault, preventing the fault from spreading or e
Rockwell
07/26/2025
What are the methods for switching operations of station transformers?
What are the methods for switching operations of station transformers?
Let's take an auxiliary power system with two station transformers as an example. When one station transformer needs to be out of service, there are two operation methods: non-interruptive power supply and instantaneous power interruption. Generally, the method of instantaneous power interruption on the low-voltage side is preferred.The operation method for instantaneous power interruption on the low-voltage side is as follows:Open the 380V power incoming circuit breaker of the corresponding sec
Vziman
07/26/2025
Inquiry
Download
IEE-Business is dedicated to serving the personnel in the global power industry.
Join IEE-Business, not only can you discover power equipment and power knowledge, but also canhnd like - minded friends!