Phase sequence indicator - for three-phase installations

When making connections to a three- phase mains supply, it is often essential to get the three phases in the correct sequence. Otherwise motors, for instance, have a tendency to rotate in the opposite direction — which can for three-phase installations have surprising results. Pumps become 1 suckers, and suckers become ... forget it. In this well-regulated nation of ours, all connections of this type must be made by qualified electricians, so nothing can go wrong. End of article, phase sequence indicator 7-90 — elektor july/august 1982 for those readers who are not qualified electricians. For those readers who are still with us, the device described here can prove quite useful. In a nutshell, when its three inputs are connected to the three phases (the neutral connection isn"t needed for this test), one of two LEDs will light to indicate a clockwise or anticlockwise phase sequence. In this connection (!), "clockwise" is defined as U, V, W (or V, W, U or W, U, V) and correspo...