MEC 20 MICROPROCESSOR ENGINE/GENERATOR CONTROLLER
PM047 Rev 13 05/03/30
71
Thomson Technology
10.6.3. VOLTAGE CALIBRATION PROCEDURE
NOTE:
To accurately calibrate the MEC 20’s
voltage sensors, an external test voltage
meter is required, with an accuracy of 0.5%
or better.
Note:
Zero Calibration must be completed before Span Calibration.
To calibrate the generator supply voltage sensors, perform the following
procedure:
10.6.3.1.
ZERO CALIBRATION
Connect an external AC voltmeter of adequate voltage range and
accuracy to the MEC 20 controller terminals associated with the voltage
phases to be calibrated. With the generator stopped, confirm there is
Zero volts on the phases to be calibrated.
In the programming mode, scroll to each of the desired generator supply
voltage phases (i.e. phase to phase or phase to neutral) with the ZERO
function selected.
Use the INCREMENT or DECREMENT push-buttons to adjust the
correction factor number to obtain zero volts on the right hand side of the
display as confirmed with the external voltmeter. The factory default
correction factor is 127. Increasing this will raise the displayed value,
conversely decreasing this value will decrease the displayed value.
Note
:
Adjusting the ZERO function with voltage applied will result in non-linear
voltage readings.
With the correct voltage displayed, press the ENTER push-button to
accept the correction factor number. Record the correction factor number
on the MEC 20 programming sheet for future reference.
Repeat the above procedure for all remaining phases of the generator
supply as required.
10.6.3.2.
SPAN CALIBRATION
Energize the generator supply voltage to the controller at nominal level.
Note:
It may be necessary to program the optional under and over
voltage shutdowns as alarms to ensure the generator will continue to
Summary of Contents for MEC 20
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