Electrical Test Tech

General Electric Multilins Protective Relaying

Multilins SR745 & SR750 Model Power Supply Issues:   Recently, I have been tasked to perform some relay testing on multiple General Electric SR relay models. But in particular, the issues experienced have been with the original model SR745 (Transformer Protection Relay) and the SR750 (Feeder Protection Relay) models. Here are examples of the Original […]

Transformer Oil Samples

Transformer oil – what is it?   Transformer oil is an oil that is stable at high temperatures and has excellent electrical insulating properties. Typical motor oil that most people think of, is not the type of oil in a transformer. Transformer oil keeps the transformer cool. It also insulates the transformer and allows electrical components to be […]

Electromechanical Relay – Contact Cleaning

Electromechanical Relay – Contact Cleaning   Equipment owners often wonder the importance of maintenance on any variety of equipment. Some owners would even say that electrical maintenance is a waste of money. I have a demonstration of an electromechanical relay with dirty contacts.   When watching the video, notice the contact below the coil begins […]

Electromechanical Relay – Basic Operation

Electromechanical Relay Operation – Above is a brief video of an electromechanical relay operating at 3 different fault magnitudes. These fault magnitudes are based off of the relay setpoint – 200% fault, 400% fault, and 600% fault. The relay set point is based off of the CT ratings and the bus/cable/load ampacity ratings.     […]

Ground Testing

This topic can be extremely complicated. So here is a quick run down. Many people often ask, “how far out do you need to run leads to the furthest rod?” This is not a linear calculation. If you are talking about a grounding delta that is 10′ x 10′ x 10′, you could be running […]

Torque – Does it matter?

  Does torque matter? The short answer, absolutely! Most electricians don’t realize that a bolt and nut is not a means for AC Current to flow through. The actual resistance of the bolt is a much higher resistance that the resistance of two sandwiched pieces of copper. When a bolt is torqued to spec, it […]

Batteries – Lewes, DE

  If you refuse to do battery maintenance, or don’t believe in maintenance at all, think again. These batteries were installed in 2006. Loose connections and lack of proper fluid levels attributed to the degraded condition. In most cases, batteries are a critical part of your electrical system and are over looked the majority of […]

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