Calibration & Meter Testing

The 2558A provides specific functions to enable meters to be calibrated accurately and efficiently.

Using the output divider and deviation

Calibrating two or more points is quick and simple. It is only necessary to preselect the number of required calibration points with the lower divider control and then use the upper control to step the output to the next calibration point. The deviation settings will then enable the output value and error of each calibration point to be displayed directly.

The deviation preset control can be used to move the output value in small increments (2 or 5 % of the step between calibration points).

This means that it is possible to finely approach the target calibration point, either from a lower value or a higher one, without exceeding it. This is particularly useful when the friction (hysteresis) of the moving part needs to be taken into consideration. In this case, the point is calibrated twice, once from a lower value and once more from a higher value and the final calibration result is the average of the two.

Using sweep

Needle sticking tests can be performed with high repeatability. It is possible to stop at any point and sweep around it in fine detail.

Power Calibration

A power calibration system can be created by using two 2558As (one each for AC voltage and AC current) together with a Yokogawa WT3000 power analyzer as the reference.

One of the 2558As acts as the master unit and provides the synchronizing oscillator signal. The required power factors is set by adjusting the phase shifter on the slave unit and monitoring the result on the WT3000. A 3 phase power calibrator system can be simply built by adding further 2558As.

Higher Current Output

To generate higher current than 72 A, two 2558As can be connected to double the output to 144 A.

Condition:

• Accuracy, stability, temperature coefficient is the sum of the individual units.
• 50/60 Hz only.

Use Existing 2558 Programs

The 2558A is backwardly compatible with the previous 2558 Model. The new 2558A supports a 2558 command mode, which means that you can switch from the 2558 to the 2558A without modifying your program. It is also possible to mix 2558s and new 2558As in the same system.

Comparison with the 2558

Front of Unit Specifications

Back of Unit Specifications

Output

* 1% to 144% of range when frequency is 50 or 60 Hz.

Accuracy

* Add 0.1% of range when output is 120% to 144% of range.