Nautel NX400, Installation Manual

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NX400 Installation Manual Connecting transformer taps and secondary wiring
Issue 1.0 2017-06-30 Page 4-1
Section 4: Connecting transformer taps
and secondary wiring
1. Before connecting ac wiring to the transformer, set the line voltage tap selections. Based on
your line to line voltage under full load, select the appropriate tap position identified on the
labels mounted on the terminal board end of the transformer. One label identifies the tap
number and the line-to-line voltage. Another label identifies the tap. All phase connections
must be set to the same tap (see
Table 4.1 and Figure 4.1 on page 4-2 ). If adjustment is
necessary, use the hardware already on each of the six phase connections to connect them to
the new tap positions, noting that the end of each phase connection consists of four copper
straps (see
Figure 4.2 on page 4-2 ). Ensure the four copper straps for each phase are evenly
split (i.e., two on top of loop, two on bottom), and secured to both sides of the tap. Be sure
to scrape any excess epoxy or corrosion off the electrical joint area.
Table 4.1: Three-phase primary winding tap nominal voltages (rms, phase-to-phase)
2. Remove the cover on the side of the transformer cabinet (see Figure 4.3 on page 4-5 ).
Remove only the screws that secure the cover.
Note
:
It is important to choose the correct tap based on the loaded line-to-line voltage (i.e., the line voltage
present when the NX400 is operating at full power and full modulation) for maximum peak
modulation capability and maximum efficiency. If the loaded line-to-line voltage falls between two
tap settings, choose the higher voltage tap (this will maximize the NX400‘s power factor).
Voltage (V ac) Taps
340 6
360 5
380 4
400 3
420 2
440 1