Basic Measurements
The 931A, 930A, and 929A measure all of the basic quantities: true-rms voltage and current, frequency and phase angle. PowerDSA™ analysis measures these quantities more accurately than ever before. Accuracy is 0.05% for voltage and current and 0.05° for phase.

The proprietary PowerDSA™ narrow-band mode even measures the fundamental signal alone, rejecting the effects of harmonics and noise. In wide-band mode, the effects of all harmonics and noise are included. Phase angle is always true, fundamental phase, and frequency is accurate even with large harmonics causing multiple zero crossings. Accuracy is never degraded, even with real-world signals.

Power Qualities
The PowerDSA™ instruments measure power quantities, too, with accuracy unprecedented for a lightweight, portable instrument. Measurements are made in accordance with IEEE standards, including the effects of harmonics and reactive power. Watts (W), watthours (Wh), volt-amperes (VA), volt-ampere hours (VAh), volt-amperes reactive (VAR), volt-amperes reactive hours (VARh), and power factor (PF): PowerDSA™ analysis measures them all, with 0.11% basic accuracy.

Harmonics
Measure harmonics and view the results graphically; as summary numbers, such as total harmonic distortion (THD), even harmonic distortion (EHD), odd harmonic distortion (OHD) or K-factor; or as individual harmonic amplitude and phase. The bandwidth extends to over 3 kHz for accurate measurement to the 50^th harmonic on 50 or 60 Hz systems, now you can know for sure what is really happening on your system.

Waveform Display
You can view the signal waveforms for both channels on the high contrast 240x64 graphic display. Both channels are normalized to Channel 1 fundamental phase, so you can see, for example, the relationship between current waveform distortions and voltage phase.

Timer
(Model 931A)
The Model 931A's timer/counter (not available on the Model 930A/929A) measures relay operating times or elapsed test times, or counts input rates and events. View times in seconds or in terms of power-line cycles. Both inputs are independently opto-isolated for safety and flexibility.

You can select from the following three-phase display modes:

• Basic three-phase display
  View voltage, current, phase, frequency and power quantities on one convenient display.
• Vector display
  View voltages, currents and phase angles with their vector representation.
• Voltage/Current Sequence display
  View voltage, current and phase along with positive, negative and zero sequence values.
• Energy display
  View voltage, current, phase, frequency and energy quantities on one convenient display.

As a power trend monitor and recording system, these PowerDSA™ instruments can verify phase relation, phase rotation, power direction, load balance and positive, negative, and zero sequence of voltage and/or current as well as calibrating and verifying in-service performance of Disturbance, Fault and Transient Recorders.

Transducer Calibration
(Model 931A)
The outstanding accuracy of the Model 931A with PowerDSA™ is ideal for transducer calibration. The Model 931A includes the necessary dc voltage and current measurements to accurately measure transducer outputs, using a separate, opto-isolated input section. With only an external source or load box, or when making in-service measurements, the Model 931A provides complete field transducer calibration.

CT/PT Ratios
Correction factors for external CTs and/or PTs, can be entered to display the measured results in input-side units. You can even measure ratios using the instrument's CH1/CH2 function. This example shows a nominal 200:1 (or 1000:5) current ratio; if Channel 1 is a CT burden voltage and Channel 2 CT secondary current, the result is the loop resistance in ohms.

Extended Measurement Ranges
For greater accuracy, the Model 09311A Auxiliary CT allows measurement of signals up to 400 amps with total basic accuracy of 0.1%. This CT mounts directly to the Model 931A, 930A, or 929A current input connectors and may be used for one two or three of the current inputs, depending on your needs.

Phone: 61 2 4353 4644 

Mobile: 0412 678 925