Xylem Aquavar, Instruction Manual

Page: 40 / 172

4.1.12 Install the NEMA 3R cover
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Figure 42: Installing NEMA 3R Cover
1. Screw without captive washer
2. NEMA 3R sticker
3. NEMA 3R cover
4. Screws to remove for taking off the NEMA 3R cover
1. Set the NEMA 3R cover over the top of the frequency converter. Align the NEMA 3R
cover with the screw holes on the top mounting plate and the screw holes on the side
of the unit.
2. Using the 6 screws provided in the bag, loosely secure the cover to the frequency
converter.
3. Torque all 6 screws to 2.3 Nm (20 in/lbs).
4. Apply adhesive label to the cover.
To remove the NEMA 3R cover after it has been installed, remove the front 2 screws on
the bottom of the unit. The cover can be removed after the other 4 screws are loosened
since the cover has slotted screw openings.
4.1.12.1 Calculating Nominal Current when Using a NEMA 3R Cover
The nominal current of a frequency converter with the NEMA 3R cover is 88% of its current
rating. For example, in a N315 standard IP21 frequency converter, the nominal output
current at 460/480V in nominal overload mode is 588 A. With the NEMA 3R cover, the
normal overload current is 0.88 x 588 = 517.4 A. The same calculation is used to calculate
the nominal current for the high overload mode.
4.1.12.2 Derating For Ambient Temperature When Using A NEMA 3R Cover
Using the NEMA 3R cover kit requires derating due to higher ambient temperatures
within the enclosure. Using SFAVM (stator flux asynchronous vector modulation) gives
greater switching control, but generates more heat than using 60°AVM (asynchronous
4 Mechanical Installation
38 Aquavar ® Intelligent Pump Controller - 150 HP to 600 HP INSTRUCTION MANUAL