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How ODES UEG/I DC current relays distinguish real coil operation from virtual voltage and transient spikes Why Voltage-Only Logic Is Not Enough in DC Control Circuits In DC trip and close circuits, engineers face three recurring headaches at the same time: High inrush current  when a trip or close coil is energized Short-duration DC bus dips and ripple  during switching events Long control cables  that pick up induced transients and create “virtual voltage” If the supervision

Anti-Pumping: A “Must-Have” That Still Goes Wrong in Practice In high-voltage circuit breaker control circuits, anti-pumping (anti-reclose on an active command) is not optional. It is written into relay protection and anti-misoperation guidelines as a   hard requirement : Before a breaker has completed one open–close–open sequence, the close coil must not receive another effective close command. Yet in real projects, two recurring issues still appear: Misuse of the breaker  o

How one “mystery trip” in a thermal power plant led to a new class of DC control relays. When a Control Box Trips “For No Reason” In 2003, a large thermal power plant ran into a problem no operations team wants to see: the local operation box on a high-voltage bay would   trip seemingly at random . No breaker failure, no misoperation recorded—just nuisance trips from the control box, often when nearby bays were being operated. The unit was safe, but the operators were not: ev

From a Single 500 kV Alarm to a Deeper Design Question During commissioning on a 500 kV transmission project in 2024, a disturbance recorder captured something protection engineers never ignore: at the exact moment a test block handle was pulled quickly, the CT secondary circuit showed a transient open-circuit condition and raised an alarm. The team did what any good commissioning crew would do: Check wiring Check terminal torque Check device contact resistance The surprise c