A power diagram indicator for high-tension circuits

Introduction and Summary The power diagram indicator was produced as a feasible, inexpensive instrument to observe dielectric or similar stray power losses that occur in high-tension circuits.¹ A cathode ray-pointer is used to trace the power diagram. It is actuated electrostatically. The pressure of the high-tension circuit applied to “quadrants” causes a proportional displacement of the ray-pointer in one axis; the pressure drop between the terminals of a condenser in series with the high-tension circuit is applied to the other pair of quadrants and gives the ray-pointer a quadrature velocity proportional to the current. The ray-pointer is thus made to trace a diagram that encloses an area proportional to the e.m.f.-current-time product.² Alternating current will produce a closed diagram or “card” having an area which is proportional to the energy of the circuit delivered per cycle. At constant frequency, therefore, the card-area measures the power applied in the circuit. The form of the card tells of many things besides the amount of power just as the steam-engine indicator card does in steam engineering.