Eltel Industries

Nehru Nagar, Bangalore, Karnataka

The Eltel ATRM-200 Automatic Transformer Ratiometer measures the transformation ratio of transformers in a ratiometric circuit. As the measurement is conducted at low flux density, this measurement is equivalent to the turns ratio of the transformer. Besides measuring turns ratio, ATRM-200 also measures phase angle deviation between the tested windings. As a perfect transformer should show no phase difference between the input and output, the measured phase angle deviation is an indicator of possible shorted turns or poor core quality. The instrument excites the High Voltage winding (HV) of the test transformer and measures the output of the Low Voltage winding (LV) in a ratiometric circuit and displays the result on a 4½ digit LCD indicator . The ATRM-200 uses 36 volts at line frequency to excite the HV winding. The measurement is not instantaneous but is conducted over a period that is equal to a whole number of line frequency periods, thereby helps to eliminate line frequency interference.

No resistance range selection is required. Wide range of test current-Three fixed ranges of 0.3-2.5A, 3-25A. 10mA to 80mA & dynamic range thus providing Continuously rated Current source over entire range. Direct digital reading, no conversion scales required True four - terminal measurement: no lead compensation required Inductive voltage kickback suppressed by instrument protection. Suitable for operation in energized switchyard conditions. Resistances of any four windings can be measured simultaneously Built-in automatic discharge circuit Protected against current lead disconnection while in use. Data Storage facility - can store upto 90 readings (without graph). Built-in timer & graph facility for use during heat run test. Displays graph of measured Resistance Vs Time - for all four channels. Correction of resistance value to reference temperature. Indicates winding temperature based on reference resistance PC & Printer interface facility. Line power: no batteries required. Uses Switch mode technology - thus it is light weight and portable