Video: SA10

Video transcript

What the SA10A measures on a circuit breaker, how it is connected, from the contacts to the coils and the travel transducer, and how to read the result. A breaker can sit closed for years and then has to open in a few 10 of milliseconds. Contact timing, mechanism travel and coil current show whether it still will: a slow mechanism, a dry linkage or a tired coil all leave a trace long before a failure. One test captures it all: 12 main and 6 auxiliary contact channels, timed to 20 microseconds

at 50 kilohertz sampling, 3 travel inputs, coils and motor, and a built in 200 amp micro-ohmmeter, in a case of about 12 kilograms. Everything is on one panel. Coils and motor on the left, 3 contact groups, one per phase, the 200 amp resistance outputs, the 3 travel inputs, the mains inlet with its earth terminal, and the display with the OPEN and CLOSE buttons. Before any cable, the order. The SA10A is earthed first. The breaker is closed, disconnected on both sides and earthed on at least one,

with its control circuits free of the SA10A. Cables go into the SA10A first, then onto the breaker. One breaking unit per phase. The grounded side of each pole goes to earth. The black sockets of the contact inputs share that earth reference. Then one red lead from the other side of each pole to input one of its phase group: A, B and C. With several breaking units in series, each unit takes its own input, A to D, in the same group, joined by short jumpers.

The auxiliary contacts go to a and b, either dry, or live with their own supply. The coils. The station supply goes into Uc and COM. CLOSE and OPEN go to the positive side of the closing and opening coils, and the coil negatives return to the supply. The motor is wired the same way, through Um and MOTOR, and only if you want to record it. Contact resistance, 4 wire. Earth the breaker first. The red 200 amp pole is tied to the chassis earth,

so it goes to the grounded side of the unit. Current cables of at least 25 square millimetres on the outside, the sense leads inside them, twisted together. Travel comes from a transducer on the mechanism, one input per phase. A digital rotary encoder is the most accurate, with a table that turns shaft angle into contact travel. Analogue linear transducers also work, and a universal kit fastens them to the breaker.

Without a PC, the basic checks still run. The display shows the breaker state and the supply voltages. CLOSE, OPEN, or both together for a close-open, and it shows the contact times and the peak coil current. With the breaker closed, CLOSE measures the resistance. The full analysis runs from the PC. Create the substation and the breaker once, with its type, mechanism, standard and rated voltages.

Open its test plan, choose an operation, confirm the voltages, and operate. Results are saved with the breaker, ready for the report. Here is a close operation. The coil current rises, dips as the armature moves, and is cut when the operation ends. The travel curve starts moving, the main contacts touch, and the mechanism overtravels and settles. The auxiliary contacts change state on either side. The software calculates contact times, stroke, overtravel,

rebound and speed, and values outside their limits turn red. Cursors and a reference curve show what has changed, and dynamic resistance separates the arcing contact from the main contact. Some tests need no outage. First trip analysis records the first operation of a breaker still in service, with current clamps on its control circuit. Point on wave switching of capacitor banks and reactors is analysed too, and so is the minimum operating voltage of coils and motor.

The internal battery powers the resistance test: charge it for 10 hours before first use. To check it, short the current cables and measure: it must exceed 195 amps. Its fuse travels in the accessory box. Calibrate every year, from the software. Maintenance and commissioning of high and medium voltage breakers, with timing, travel, coils, motor and resistance recorded in the same operation. Circuit breaker testing, from Amperis.