Megger MWA300 Series User manual

Safety is the responsibility of the user
Only qualified and trained personnel should operate the MWA300. Operator must read and understand this entire instruction manual prior
to operating the equipment. Operator must follow instruction manual and attend to the equipment while in use. In the event of equipment
malfunction, the unit should immediately be de-energized and returned to Megger for repair. The safety precautions herein are not intended to
replace your company’s safety procedures.
Refer to IEEE 510 - 1983, “IEEE Recommended Practices for Safety in High-Voltage and High-Power Testing” for additional information.
Read the MWA300 manual before operating equipment.
This guide is not meant to replace manual.
Connect Leads / Power / Ground
After
INT/EXT switch
set to EXT
(PC operation)
Before
Black to Low
Voltage Secondary
or Tertiary Winding
HIGH-VOLTAGE EQUIPMENT!
MWA300 Quick Start Guide
MWA300_QG_EN_V01
1
Red to High
Voltage
Primary Winding

Turn Instrument On, select MWA from instrument list on
PowerDB which brings up “Select a Form” box.
Select 3Ø Turns Ratio & Winding Resistance form.
This guide uses this form as an example. Allow 30-60
seconds for PC to communicate with Instrument. See
manual for any PC connection issues.
Fill out Nameplate information (minimum info listed below)
Input Desired Test Settings
At this stage, connect Test leads to transformer under test.
Note color coding and marking on leads. Match to transformer
bushing markings.
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4
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Test dialog appears once test begins:
Winding Resistance Test –depress # to test all 3Ø’s for tap or
depress highlighted box to begin testing individual phase:
For automated winding resistance testing, MTO Test Wizard can
be used if all critical nameplate information is filled in from step
4) above.
Select and start the Ratio (TTR) Test by depressing # below.
Testing will follow Nameplate input from 4) above:
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11 Once test begins to run for any resistance, following
screen will appear:
Controls are as follows:
i) Test Setup: allows changes to test parameters, which can be seen in step 4 above (and described in
section iv below). This button is ‘greyed out’ once testing begins or MTO instrument connection is not
established.
ii) Test Mode: enables various testing to Start, Continue, Save Results etc. as testing is conducted. This
button guides operator through testing, providing instruction for next steps.
iii) Abort/Exit: allows disruption of test and/or exiting once test is concluded.
iv) Results Graph: plots resistance results for diagnostic review. This is useful in determining that each
past result is following an expected pattern. Different OLTC tap changers develop different shaped
patterns such as V, Saw Tooth, Slope curves. Familiarity with these tap changers helps improve diagnostic
capability.
v & vi) Measured Resistance: result with color background changes using “Reading Stability + Time
for stable reading” setting as shown in section iv above. When condition is reached, background turns
green.
12 Once all tests are complete and this window closes,
results will appear on test form:
Saving Results – once test is completed, form will prompt to save result.
After name is entered, results are automatically saved as each test is
completed.
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