Regulating Apparatus, Current - Acceptance Test

What it is

This form is the acceptance record of a constant current regulator for an airfield lighting series circuit: FAA type L-828 (regulator without monitor) or L-829 (regulator with monitor), Class 1 at 6.6 A or Class 2 at 20 A, Style 1 with three steps or Style 2 with five. It records the safety precautions, the visual and mechanical inspection against the FAA AC 150/5345-10H construction requirements, insulation resistance and winding resistance against the manufacturer values, the dielectric withstand levels where a field repeat is made, the output current at every step with the load and input voltage of each reading, the control response and control checks, the open-circuit and over-current protective device tests, the input power interruption test, the monitor settings and functional checks on an L-829, and efficiency, power factor and crest factor at the top step. The verdict needs the top-step output current from the section that matches the nameplate class and style. On a series circuit other than airfield lighting the output current is recorded against the manufacturer values and the verdict stays ungraded, while the FAA timing and protection values still raise issues when exceeded.

Why it is performed

A series lighting circuit works because every lamp sees the same current whatever the number of lamps and whatever the input voltage does, and the regulator is the only thing that makes that true. A step that delivers the wrong current changes the intensity of every light on the runway or taxiway at once; a slow or unstable step change, or a start-up that lags, shows as flicker and delay to a pilot; and the open-circuit protection stands between a broken series loop and an output voltage that can reach 4,250 V or more. The acceptance record proves each of those against the values FAA AC 150/5345-10H sets, with the test method and the procedure document named for the protective device tests, because the specification lists them as production tests and the field repeat has to say how it was done safely. The record also keeps insulation and winding resistance for comparison with the factory values over the life of the unit.

When it is performed

The form is an acceptance record for a regulator installed on its series circuit. The output current, control response, protective device and monitor tests are field tests; the dielectric withstand, open-circuit output voltage and input power interruption tests are factory or certification tests under FAA AC 150/5345-10H, repeated in the field only where the owner requires them and the manufacturer method makes them safe, otherwise the factory report value is recorded, and a field dielectric level, where one is applied, is the owner or manufacturer call. The specification sets no recurring interval and the form carries none; insulation resistance readings are compared at the same voltage and temperature over time.

How it is typically performed

Identification sets the FAA type, the application, the class and style, and the nameplate ratings; the class and style must agree with the output section filled, since the stability band and the over-current points follow the class. Input and control power are removed before the cabinet is opened, and the energized series circuit is never opened by hand. The visual inspection checks the nameplate, warning plate, wiring diagram, selector marking, front ammeter, surge arresters, ground terminal, enclosure, oil level and the L-829 monitor. Insulation resistance and winding resistance are measured by analogy with the IEEE C57.15-2017 method and compared with the manufacturer values. With the actual lamp load, a resistive test load or the reactive case with 30 percent of the isolation transformer secondaries open, and the input voltage recorded, the output current is read at every step from a reference ammeter, and at the top step also with the output short-circuited and at 95 and 110 percent of nominal input voltage. Control response records the time to a stable output after a step change, the excursion after settling, the start-up delay and the remote control voltage, and the panel ammeter is compared with the reference at the top step. The protective device tests record the method and the procedure document: open-circuit trip and reset by a manufacturer test facility or test mode, a remote-operated output switch with personnel clear, or the factory report value; over-current trip at 5 and 25 percent over the class current by manufacturer test mode or sense-circuit injection, with the test current entered so the form knows whether the trip time is graded. Input interruptions of 10, 100 and 500 ms, then 1 and 5 s, record the time to restored output. On an L-829 the five monitor faults are simulated and the alarm delays and lamp settings recorded. Input watts and volt-amperes and output watts at the top step give efficiency and power factor; peak and RMS output current give the crest factor. Return to service re-enables the open-circuit protection and reconnects the arresters.

What gets recorded

Identification: FAA type, application, class, style, rated output, input voltage, frequency and current, control voltage, rated output current, oil volume, nameplate and location data and the series circuit served. The safety precaution and visual inspection items. Insulation resistance and winding resistance readings with temperature, manufacturer minimum and margins. Dielectric withstand levels, basis and results. Test conditions: load connected, percent of rating, nominal and measured input voltage, control mode, reference ammeter. Output current per step for the class and style section in use, with the short-circuit and 95 and 110 percent input readings at the top step, or the manufacturer tolerance and deviations on another series circuit. Control response: settling time, excursion, start-up delay, remote control voltage and supply, panel and reference ammeter readings. Protective devices: methods, procedure documents, test currents, trip and reset times, open-circuit output voltage and its limit. Input interruption times and responses. Monitor alarm delays, lamp settings and functional checks. Input and output power, efficiency, power factor, peak and RMS current, crest factor. Return-to-service checks, ambient temperature and humidity, test equipment, comments and deficiencies.

How results are evaluated

Two gates come first: FAA AC 150/5345-10H grades an airfield lighting series circuit only, so on another series circuit the verdict stays ungraded; and the class and style selected must agree with the output section filled, or the verdict is indeterminate with an issue unless another criterion fails. The graded core is the top-step output current from the matching section. Every step current, and the top-step readings with the output short-circuited and at 95 and 110 percent of nominal input voltage, must lie within the allowable range for the class, style and step: within 0.10 A of nominal on Class 1 and within 0.30 A on Class 2, both ends of the range passing. Control response: the output settles at the selected step within 5.0 s and then holds within the class stability band, 0.1 A on Class 1 and 0.3 A on Class 2, and where a start-up delay is used the current reaches the output within 2.0 s of turn-on. Protection: open-circuit protection operates and resets within 2.0 s; over-current protection operates within 5.0 s at 5 percent over and within 1.0 s at 25 percent over, and resets within 2.0 s, a trip time being graded only when the test current lies in the window from the over-current point to 10 percent above it. After an input loss of up to 500 ms the output is restored within 1 s. On an L-829 the monitor waits at least 5.0 s before alarming on faults c, d and e. Efficiency at the top step must reach the minimum the specification sets for the rated output, power factor must be at least 0.90 at 10 kW or less and 0.95 above, entered as a ratio, and the crest factor must be less than 3.2, so 3.2 itself fails. Recorded with an issue when exceeded, never graded: insulation and winding resistance against the manufacturer values, the dielectric levels, the remote control voltage, the open-circuit output voltage against the greater of twice rated watts over rated amperes and 4,250 V, the panel ammeter within 1 percent of maximum output, the failed-lamp and re-arm settings, the 1 s and 5 s interruptions, and the checklist items.