Understanding the Frequency Calculation of AC Generators

How is the frequency of an AC generator calculated for a 1500 rpm, 2-pole machine?

• A. 20 Hz
• B. 25 Hz
• C. 50 Hz
• D. 60 Hz

Answer: (B)

To determine the frequency of an AC generator, you can use the formula that relates the speed of the generator (in revolutions per minute), the number of poles, and the resulting frequency in hertz. The formula is: \[ \text{Frequency (Hz)} = \frac{\text{Speed (RPM)} \times \text{Number of Poles}}{120} \] In this instance, for a 1500 rpm, 2-pole machine, you substitute the values into the formula: 1. Speed = 1500 rpm 2. Number of Poles = 2 Plugging in the values: \[ \text{Frequency} = \frac{1500 \times 2}{120} \] Calculating that gives: \[ \text{Frequency} = \frac{3000}{120} = 25 \text{ Hz} \] Thus, the frequency of the AC generator is 25 Hz. This calculation is essential in understanding how the mechanical design and operational characteristics of the generator directly affect the electrical output frequency. The frequency determines how the AC power can be utilized and is crucial for synchronization within power systems and equipment.

Understanding how to calculate the frequency of an AC generator is like unlocking a hidden gem in electrical engineering. It’s a fundamental skill that not only prepares you for the Registered Electrical Engineering Licensure Exam but also grounds your understanding of power systems that are integral to our everyday lives. So, how do you figure it out? Let me walk you through it!

The Formula You Need to Know

At the heart of frequency calculation is a simple formula that brings together the speed of your generator and the number of poles it has. The magic equation is:

[ \text{Frequency (Hz)} = \frac{\text{Speed (RPM)} \times \text{Number of Poles}}{120} ]

Now, let’s break that down a bit. The speed is measured in revolutions per minute (RPM), and the number of poles is simply how many poles the generator has.

For our example, let’s say you have a generator running at 1500 RPM with 2 poles. Plugging our numbers into the formula, we have:

1. Speed = 1500 RPM

2. Number of Poles = 2

When you put those values into the formula, it looks like this:

[ \text{Frequency} = \frac{1500 \times 2}{120} ]

Time for a little math! What do we get when we calculate that?

Getting to 25 Hz

Doing the math, we find:

[ \text{Frequency} = \frac{3000}{120} = 25 \text{ Hz} ]

And there you have it—the frequency for this particular AC generator is 25 Hz. Isn’t it interesting how just a few numbers can tell you so much about the machine's output? This insight is pivotal as the frequency impacts how the AC power is utilized across various systems, playing a crucial role in devices and infrastructure.

Why This Matters

So, why should you care about this frequency calculation? Well, understanding frequency isn't just a theoretical exercise; it has practical applications in synchronizing power systems and ensuring they work efficiently. Think about it—if you have different machines operating at various frequencies, you could run into some significant problems. Equipment failures, inefficiencies, and costly downtime could become all too common.

By mastering these calculations, you’re not just preparing for an exam—you’re gaining a skill that will help ensure power systems operate smoothly and reliably in the real world.

Tying it All Together

In the grand scheme, knowledge of how to calculate frequency ties into larger concepts, like power generation and distribution. As you study for your licensure exam, remember that every detail, every formula, has relevance—especially when tackling complex systems that we often take for granted.

So, the next time you're faced with a question about AC generator frequency, remember this formula. It’s a small piece of the puzzle but one that fits into a much larger picture of electrical engineering. Keep practicing these calculations, and you'll feel more confident as you approach your exam day. Happy studying!