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Magtrol Model 5300 Three Phase Power Analyzer

Chapter 9 - Calibration

Since the current calibrator output is usually a low

impedance with low compliance voltage, the 5300's

current measuring shunts are the circuit's major

resistance. Let's take a representative example and

compute the resulting phase shift:

Let L = 10 µhenries (total of shunt, wiring, etc.)

Let R

SHUNT

= 0.011 Ohm; R

WIRING

= 0.01 Ohm

R = 0.011 + 0.01 = 0.021 Ohms

Let F = 60 Hz ∴ 2 π FL ≈ 0.004

θ Arctan (2 π FL /R) = Arctan (0.004 /0.021)

θ ≈ 11 degrees, or about 1.8 % measurement error. This

error can be eliminated by adjusting the calibrator's

variable phase shift control. This demonstrates the need

for care in making power analyzer calibration

measurements.

CALIBRATION VERIFICATION

Refer to Figure 16 for the recommended test setup. If

other test equipment is used, appropriately modify the

test steps for your equipment. Each of the 3-phases

(φ1, φ2, φ3) are identical and are individually tested.

The same procedure is used for each of the 3-phases.

Potentially lethal voltages are used in

the following test steps. Take

appropriate precautions to avoid

electrical shock. Refer to your calibrator

operator manual for operating

instructions. Because these calibrators

generate lethal voltages, extreme care is

necessary.

The three steps of the calibration verification are as

follows:

1. Volts Calibration Check

2. Amperes Calibration Check

3. Watts Calibration

Set both the VOLTS and AMPERES calibrators to

standby mode.

VOLTS CALIBRATION CHECK

φφ

φ1

DC:

1. On the 5300 PA, press the 150 volts range push-

button.

2. Set the volts calibrator for zero volts DC and operate

mode.

3. The 5300 VOLTS display should read zero +

0.0001% max of volts full scale range.

4. Set volts calibrator for + 150 volts DC.

5. The 5300 VOLTS display should read 150.0 volts.

Record the VOLTS readings.

6. Set the calibrator for - 150 volts DC and repeat the

above step. Record the VOLTS readings.

7. Repeat the above for the 300 and 600 volts ranges.

Lethal voltages are present. Take

appropriate safety precautions.

8. Compare the above readings to the values given in

Section 2, Specifications.

The (+) and (-) readings should be within ± 2 least

significant digit (LSD) of each other.

AC:

1. Set the volts calibrator for 60 Hz and repeat the

volts checks as outlined in the DC test above.

NOTE: If a beat frequency effect is

experienced between the

calibrator output and the 60 Hz

power line frequency, try setting

the calibrator for 80 Hz instead of

60 Hz.

2. Set the volts calibrator to standby mode.

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