An efficient power compliance testing regime requires versatile equipment to accurately trial both AC and DC systems coupled with an ease of use
Electronic devices and instruments installed on commercial aircraft require stringent AC and DC power system compliance tests in accordance with generic avionics standards such as RTCA DO-160 and MIL-STD-704. The main purpose of compliance testing is to simulate the range of power characteristics that avionic electronic devices and instruments may experience during their lifetime, and doing so ensures that the test subject is capable of meeting the performance requirements under such electrical operating conditions.
The tests covered by avionics standards such as MIL-STD-704F are divided into a number of power groups (see table, Power Group Acronyms) based on the input electrical power for utilization by the instruments. The power groups detailed in the table have test frequencies consisting of constant values, noted as 400Hz for example, or variable ranges from 360-800Hz when not noted.
The acronyms in the table are further appended with a code number that indicates the aircraft electrical operating condition together with a test number to define the specific test item under the individual power group. One such example is the SAC303 test item, which defines the Abnormal Frequency Transient test conditions. This is test number 3 of aircraft electrical operating in abnormal condition defined by the MIL-STD-704F standard. Please note, a similar nomenclature method is also applied for defining each test item for other avionics standard procedures such as RTCA DO-160G.
THE GUI FRONT-END
The Chroma Softpanel is a graphical user interface that provides extraordinary capability and convenience to users for controlling the unit. The avionics softpanel is designed to be user friendly, easy to operate, and most importantly, able to deliver the required avionics standard’s test items.
The avionics softpanel consists of two parts. The first is the fixed-mode page (Fig 1) that can be viewed as the GUI extension of control for an AC source product, and the second part consists of the test items coverage page that is required by the avionics standard.
TEST SYSTEM POWER SOURCE
In order for the avionics softpanel to fully accomplish its tasks, an AC source like the Chroma 61512 has to be used. This unit is a highperformance AC power source that is capable of simulating a wide range of AC line conditions, and meets market requirements by providing the ability to simulate various AC line input conditions as well as measurement of the critical characteristics for unit under test (UUT). These features make the 61512 AC source ideal for commercial, power electronics, avionics, and regulatory test applications, including bench-top RD design verification, quality assurance, and mass production. Using state-ofthe- art PWM technology, the 61512 can deliver maximum output voltage up to 300V AC with typical distortion of less than 0.3% at 50/60Hz and output frequencies from 15-1,500Hz. The AC+DC mode extends the applications by not only providing pure AC voltage, but also a DC component for DC offset testing.
POWER TESTS AND RESULTS
The Chroma 61512 is capable of providing precision measurements that include RMS voltage, RMS current, true power, power factor, current crest factor, and more. By applying advanced DSP technology, the 61512 easily simulates power line disturbances through LIST, PULSE and STEP modes, and allows users to compose different harmonic components in order to synthesize various harmonic distorted waveforms. By applying this advanced feature, users can program a sweep frequency component incorporated with the fundamental voltage for finding the resonance points of the UUT, thus providing the user with in-depth analysis results. To simulate the natural waveform, the 61512 provides an external analog input used to amplify the analog signal generated from arbitrary signal generator. The user can implement this feature to duplicate a unique waveform observed in the field. The user-friendly interface allows quick access to the 61512 AC source’s functions through the large LCD front panel display with a clearly indicated keypad. The GPIB (IEEE488.2), RS-232, USB, and Ethernet interfaces are available for users as standard to allow control of the AC source remotely.
See more information about Chroma High Performance AC Power Source – 61500 series.
In Recent news, Aerospace Testing International covered our Adaptable Power Tester in a Magazine
(Read it below or at this link).