Vertical bands in photo are an artifact of camera exposure and screen update, the screen looks great to the eye


The CTMP-2006 was developed as a CT test set but has been enhanced to perform a precise ratio test of any transformer; current, potential or power. The instrument has 0.1% accuracy over the entire measurement range. Accuracy is essential in the detection of partially shorted turns and manufacturing errors. Unlike some lower quality instruments, the CTMP-2006 will detect a one turn error on a 3000/5 CT. An undetected error in a bulk power revenue metering installation could have significant financial consequences. A relay misoperation that interrupts a major circuit could also prove costly. The CTMP gives you the precision at high ratios that others don't.

This precision is made possible by the following features:

1) A highly accurate 16 bit A/D converter. We could save money with a lower resolution chip but we know your quality testing program demands precision.

2) The Calvada Technologies AC measurement algorithm. We don't convert AC signals to DC for measurement. The CTMP uses a proprietary sampling algorithm, time division multiplexing and a single A/D converter to accurately extract amplitude and phase angle information from two AC signals. Voltages are measured to an accuracy of better than 0.05% and any error in conversion gain is applied to both voltages cancelling that error. The collection of an array of time domain samples for each signal will allow the application of an FFT algorithm if it is ever desired to expand functionality into the power quality area. Custom programming is available for customers who want this. Our accuracy is an order of magnitude better than the typical "competitive" CT test set.

3) A wide range of excitation voltage, from less than a volt to 1000VAC, prevents the loss of resolution that inevitably occurs with fixed excitation test sets when testing high ratio transformers.

The CTMP will ratio current transformers from 5/5 to 100,000/5. The potential transformer range is from 1/1 to 5,000/1 and this range, of course, also applies to power transformers. The instrument displays the excitation voltage applied to the CT secondary (or PT primary), the induced voltage in the CT primary (or PT secondary) and the angle between them (polarity). Ratio to 5 for current transformers and 1 for potential and power transformers is calculated and displayed. The ratio mode offers several menu selected functions:


1) CT ratio, low range. Excitation range is 0-200VAC with meter autorange to 0-20VAC when output is adjusted below 20V. Induced primary voltage range is 0-0.32VAC for excellent resolution with the single turn primary normal to this test. CT low range is used for all current transformers with a ratio of 10,000/5 or less. Ratio is calculated at any induced primary voltage over 0.033VAC allowing an accurate test of small, low ratio, CT's. Ratio data may be transmitted via RS-232 to a PC. This allows rapid creation of a data sheet.

2) CT ratio, high range. This mode is used for ratios over 10,000/5. Excitation is 0-1000VAC with an induced primary range of 0-0.32VAC. As with the low range ratio is calculated at any induced primary voltage over 0.033 allowing an accurate ratio of a 100,000/5 CT ! As with the low range, ratio data may be transmitted via RS-232 to a PC.

3) PT ratio, low range. Mode is used for potential transformers with an expected ratio less than 60/1. Excitation is 0-200VAC with meter autorange to 0-20 when applicable. Induced secondary voltage range is 0-3.2V to maintain accuracy with lower ratio transformers. Data may be transmitted to a P.C.

3) PT ratio, high range. Mode is used for potential transformers with an expected ratio equal to or greater than 60/1. Excitation is 0-200VAC with meter autorange to 0-20 when applicable. Induced secondary voltage range is 0-0.32V. Data may be transmitted to a PC.

The link below is a movie clip of a production CTMP-2005 performing a ratio check prior to final assembly into the case. A relay test set is used to power the output circuit with a stable source to facilitate calibration. Note the low noise and precise ratio measurement result even while the output control is moved to simulate power fluctuations. The CTMP delivers amazing accuracy with any sinusoidal 60HZ source even during transients caused by motor starting and other load fluctuations !!

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