Give Until it Hertz - The Battle Over Frequency - Short #271 · HVAC School - For Techs, By Techs summary

Key takeaways

The frequency war between 60 Hz and 50 Hz had significant historical implications for electrical engineering and infrastructure.
Different regions adopted different frequencies based on their technological advantages, leading to enduring incompatibility.
Modern advancements like VFDs illustrate that flexibility and adaptability in technology can overcome historical limitations.
Standardization in engineering should be approached with caution as it creates long-lasting infrastructure challenges.

Summary

The Forgotten Frequency War

This episode explores the history and impact of the frequency war post the War of the Currents, detailing how alternating current (AC) frequencies diverged globally. The battle between 60 Hz favored by American companies like Westinghouse and 50 Hz adopted by European entities like Siemens illustrates the chaos that ensued in the early 1900s due to inconsistent standards across various regions.

Standardization and Its Consequences

The podcast articulates how the U.S. settled on 60 Hz as the standard during the merging of electrical grids in the 1910s, while Europe adopted 50 Hz, creating an enduring split. Listeners learn about the significant implications this had on machinery performance and electrical infrastructure, with mismatches leading to compatibility issues, inefficiencies, and operational challenges.

The Technology Taming the Frequency Divide

Discussion shifts to modern innovations like Variable Frequency Drives (VFDs) that offer flexibility in operating frequencies, alleviating some of the historical constraints posed by the frequency war. VFDs allow for adjustments in motor speed irrespective of grid frequency, illustrating a leap in technology that reconciles the past with new potential.

Lessons Learned from the Frequency War

The episode wraps up by underscoring the importance of thoughtful standardization in engineering and how historical decisions shape present practices. A reminder is issued about the adaptability that modern technologies provide and the potential for future developments informed by past challenges.

Show notes

In this short podcast episode, we go back into the history of the trades, namely the battle over frequency (and how each side had to give until it hertz).

The low hum of motors is alternating current: electricity moving back and forth through copper 60x per second (in the USA and Canada, at least). In another version of history, that pulse could be 50x per second instead (as in much of the remainder of the world). The forgotten frequency war is the lesser-known sequel to the war of the currents.

Tesla's AC power prevailed over Edison's DC, but different motor and generator companies chose different alternating current frequencies. Westinghouse chose 60 cycles per second, whereas General Electric experimented with 25-40 cycles per second, and Europe-based Siemens and AEG standardized around 50 hertz. These different frequencies set the rhythm for everything that turns or glows, and electric parts that didn't match often failed. Nevertheless, the engineers of the companies defended their own frequencies.

In the 1910s, the US began merging electrical grids to set a single standard. Westinghouse had the most dominant technology at the time, and 60 hertz became the norm in the USA. However, across the pond, 50 hertz made more sense for the European infrastructure that was in place and being rebuilt after WWI, and it was solidified by the rebuilding efforts of WWII. As a result, roughly 2/3 of the planet uses a 50-hertz frequency.

The two frequencies are incompatible because motors will travel at a different speed than their design while drawing the same current, leading to reduced capacity or overheating. In the 1960s, international companies produced dual-rated compressors and motors, but global trade is still complicated by different frequencies, and moving entirely to a single frequency is impractical due to the infrastructure disruption required. However, modern VFDs and inverter technology can change frequencies as they enter the motor, thus solving the battle over frequency and reminding us that flexibility is the real future.

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Give Until it Hertz - The Battle Over Frequency - Short #271