Tag: relay

Anti-Pump Relay

The anti-pump relay provides an important function feature in control circuits. Without the anti-pump function, if the user connected a maintained contact in the close circuit, and the circuit breaker were closed into a fault current, the protective relays would cause an immediate trip action, but the maintained contact in the close circuit would initiate […]

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 […]

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.     […]