Providing power for testing complex electronic devices requires reliable, high-performance AC sources which often also deliver DC power. Fortunately, Transcat | Axiom Rentals offers a variety of versatile sources that can not only supply AC/DC power but also monitor its electrical parameters over widely changing environmental conditions. To support AC/DC power testing according to numerous industrial and military standards, these power sources are available with software to coordinate standards-based AC/DC power testing with single-, two-, and three-phase power supplies.

Industrial and military standards provide guidelines for evaluating a device under test (DUT) on AC or DC power. Industrial standards such as IEC 61000-4-11 and IEC 61000-4-13 from the International Electrotechnical Commission (IEC) and military standards such as MIL-STD-704 are just a few of the solid guidelines for AC power testing; they are typically programmed into the test software available for modern AC power sources.

As an example, military standard MIL-STD-704F, developed for testing the electric power requirements of aircraft avionics and electronic systems, defines AC requirements for the many component parts of aircraft electrical power systems, including main and emergency power sources, power conversion equipment, control and protection devices, and interconnections such as wires, cables, and connectors.

Measurement-grade AC electrical power sources typically include power conversion circuitry and can supply DC power over wide ranges. Such sources may produce AC and DC power separately or simultaneously and provide precise control of key electrical parameters, such as voltage, current, fundamental frequencies, harmonic frequencies, phase, and even harmonics. 

The size of an AC + DC power source will depend on its functionality and output power, with housings ranging from single-space (1U) rack-mount enclosures to much larger, floor-standing racks of units in series or parallel for generating high power levels. Standards testing is usually simplified by remote control of a power source through an available interface, such as USB, GPIB, or RS-232, using an external computer with the appropriate test software.

 

Perusing AC/DC Power Sources

Many of the latest measurement-grade AC power sources also provide DC power and pack impressive control capabilities into compact housings. The California Instruments Asterion™ (AST) AC + DC power sources from Ametek® Programmable Power are among the many power sources available from Transcat | Axiom Rentals. Well suited for avionics, commercial electronics, and telecommunications testing, the AST line includes models AST1503, AST6003, and AST18K3 with a variety of power levels and testing capabilities.

The California Instrument AST1503 fits a 2U 19-in.-wide rack-mount enclosure opening but delivers as much as 1500 VA (1500 W) output power in single-phase mode and as much as 500 W output power per phase in three-phase connections. The maximum current per phase depends on the corresponding output voltage, with as much as 1.25 A RMS at 400 VAC, 2.50 A RMS at 200 VAC, and 5.00 A RMS at 100 VAC. The compact power source also provides DC power simultaneously with the AC power, with as much as 1.0 ADC current/phase at 500 VDC, as much as 2.0 ADC/phase at 250 VDC, and as much as 4.0 ADC/phase at 500 VDC. The available current is three times as much in single-phase mode as the amount of current for each phase in three-phase mode, such as 15.0 A RMS single-phase current at 100 VAC and 6.0 ADC single-phase current at 250 VDC.

As with the other AST AC/DC power sources, the AST1503 includes a constant-power operating mode which enables each AST power source to supply full power even when the full-scale rated voltage is not available. In this mode, the power source supplies as much as 200% of its rated maximum AC and DC current if the voltage drops to 50% or less of its full rated value, enabling the power source to maintain consistent output power under changing voltage conditions. This power source is well equipped for remote computer/software control, with RS-232, GPIB, USB, and Ethernet interfaces.

The California Instrument AST6003 AC + DC power source is twice the height of the AST1503, in a 4U rack-mount enclosure, but delivers as much as 2000 VA (2000 W) power per phase in three-phase connections and as much as 6000 VA (6 kW) power in single-phase operation. It provides as much as 5 A RMS current per phase for three-phase operation at 400 VAC, 10 A RMS current per phase at 200 VAC, and 20 A RMS current per phase at 100 VAC, with three times those maximum AC current values for single-phase operation. Maximum DC output current per phase for three-phase connections is 4 ADC at 500 VAC, 8 ADC at 250 VDC, and 16 ADC at 125 VDC, with three times each maximum AC and DC current value when in single-phase operating mode.

For those in need of more power and willing to manage a 14U rack-mount-height enclosure, the California Instrument AST18K3 AC + DC power source provides as much as 18 kVA (18 kW) power in single-phase mode and as much as 6 kVA (6 kW) power per phase for three-phase connections. It also provides much higher current levels than the two smaller AC/DC power sources, with maximum AC power of 15 A RMS/phase at 400 VAC, 30 A RMS/phase at 200 VAC, and 60 A RMS/phase at 100 VAC, with three times those maximum current values at the same voltage settings in single-phase mode. The maximum DC current/phase for three-phase setups is 12 ADC at 500 VDC, 24 ADC at 250 VDC, and 48 ADC at 125 VDC, with three times those maximum current levels for single-mode operation at those voltages.

One of the more impressive compact AC + DC power sources, with numeric keypad and 4.3-in.-diagonal color liquid-crystal-display (LCD) screen mounted on the front of a 4U enclosure for ease of use, is the Pacific Power Source 3150AFX-2A AC + DC. It integrates a digital oscilloscope for accurate measurements and advanced digital power conversion technology to provide single-, split-, and three-phase operating modes. Packed into a 19-in.-wide (483-mm-wide) chassis for benchtop or rack-mount use, with numerous protective functions and a sleep mode to save power, it is well suited for commercial, industrial, and military power testing.

It provides as much as 125 A RMS AC current and 62.5 A DC current in single-phase mode for AC voltages from 0 to 333 VAC and DC voltages from 0 to 425 VDC, generating as much as 15 kVA (15 kW) AC power and 15 kW DC power. In split- or three-phase modes, the AC + DC power source is rated for 41.7 A RMS maximum AC current and 21.0 ADC maximum DC current. A model 3150AFX-2A can function as a controller for as many as five additional 3150FX-NC (no controller) power sources in parallel or series system configurations. A model 3150AFX-2A includes LAN, RS-232, and USB interfaces with options for WiFi and GPIB for remote control connections. Each 3150AFX-2A features versatile characterization capabilities and can measure AC voltage (in V RMS), AC current (in A RMS), current crest factor, power (in kW), power factor, DC voltage, and DC current. It allows DC frequency to be set with 0.01-Hz resolution over a standard range of 15 to 2000 Hz.

An emerging, fast-growing application for AC + DC power sources is for electric-vehicle (EV) infrastructure testing, such as for EV battery charge stations, and the California Instrument SQ0045 AC + DC power source is a candidate for this application. It has been an effective power source for simulating urban power grids (see “Grid Simulators Are Smart Power Sources”) and is well suited for EV infrastructure power testing.

Capable of single- or three-phase operation, the SQ0045 provides as much as 45 kVA (45 kW) power. AC voltages can be set from 0 to 166 V RMS in the low range and 0 to 333 V RMS in the high range, with DC voltages of 0 to 220 VDC in the low range and 0 to 440 DC in the high range. The SQ0045 includes flexible test functions, capable of measuring frequency from 16 to 905 Hz with 0.1 Hz or better resolution, AC voltage from 0 to 400 V RMS, DC voltage from 0 to 500 VDC, AC current from 0 to 150 A RMS, DC current from 0 to 400 ADC, AC power from 0 to 15 kVA, and DC power from 0 to 15 kW.

For higher power, the California Instrument MX90 AC/DC power source is a three-phase unit capable of as much as 90 kVA (90 kW) power. The single-chassis, floor-standing source delivers as much as 200 A from 0 to 150 VAC and as much as 100 A from 0 to 300 VAC. It has typical efficiency of 85% and can be set for AC frequencies from 16 to 819 Hz. More information on any of these units can be found by contacting a Transcat | Axiom Rental Account Manager for guidance at 800-264-4059.