6.6A Series Converter to 125VAC, 600 VA Power Adapter
The 600 VA power adapter converts 6.6A 60 Hz series current to nominal 125 VAC voltage.
Power input cable is a FAA L-823 Class A, Type II, and Style 1 Male Plug. This input connector is designed to mate with the standard female receptacles found on all FAA certified Isolation transformers. The female output cable FAA L-823 Class A, Type II, and Style 7 female receptacle. The isolation transformers can be provided but are not part of the Power Adapter. The power adapter is encapsulated with a two-part resin epoxy that has very high thermal conductivity and electrical insulation properties capable to be operating under the range of -40° to 130°C.
A Ferroresonant transformer designed for 6.6A, 60 Hz series current airfield circuits convert the energy of the series current into a stable voltage source of 60 Hz. The output is a quasi-sinewave regulated AC voltage
that can be used to power most electronic devices. Voltage regulation is maintained at the transformer output from Open Circuit to full load, when the input sees the input current range between 2.7A – 6.7A, 60Hz. The secondary is design that a continuous short circuit of the output will cause no harm to the transformer, regulated voltage will return once the short circuit is eliminated. Output voltage will be regulated within a range of 100 – 140 VAC with a maximum of 600 VA loading. Temporary overloads up to 750VA can be withstood, only sacrificing a drop in output voltage. FAA requires the use of isolation transformers to be used in all series circuits and the loads connected to the circuit. These isolation transformers were originally design for resistive loads of incandescent and halogen filament lamps. As such the voltage needed on the output is relatively low. Having a lower supply voltage with a constant current source cause the load to become highly inductive with respect to the isolation transformer. The high inductivity causes a poor power factor. The relationship of the current signal as compared to the voltage drop across the primary of the converter is reflected in the power factor of the unit. Efficiency of the transformer converter is the relationship of the IR losses of the input and the output coils along with the heat losses of the effective series resistant (ESR) of the capacitor used in the inductive/capacitor loop that regulates the output voltage so well. The best efficiency and voltage regulation would be experienced when used with two series connected FAA certified L-830-14 6.6A / 6.6A isolation transformer or two series connected FAA certified L-830-15 20.0A / 6.6A three to one step down transformers. The transformers would be connected to a bridge cable to combine the secondaries of the isolation transformer and provide the adapter with the properly phased current. Their electrical design characteristics of this isolation transformer are rated at maximum load of 600 Watts at a resistive load of 29.6 ohms, and a maximum open circuit voltage of 145 V rms value at no load.
Data below was taken using two 500 Watt 6.6A / 6.6A isolation transformers transformer on a SCR circuit with incandescent lamps loads, rated at the following loads either 300 W, 600W, 640W, & 750W. The regulator used was a 10kW Phase Cut SCR, at the following loads, 25%, 80%, & 50% to verify operation at different crest Factors. Reading taken directly on the primary and secondary of the power adapter, after the connection to the two isolation transformers in series with bridging cable.
The isolation transformers and the voltage converter can be used in circuits powered either by Ferroresonant or SCR controls Constant Current Regulators (CCR) that exhibit crest factors of 3.5 or less. Ferroresonant type CCR’s will have a more conservative crest factor often in the 1.5 range this will allow a slightly higher power factor at lower current inputs closely approaching the range of 0.89 – 0.92.
