Specifications

There are numerous issues to consider when sizing an enclo-
sure for a drive: motor nameplate rating, type of material, style
and appearance, environment, and internal volume of the
drive. Two things affect the internal volume; first, the amount of
depth for safe clearance of components mounted inside of the
enclosure; second, the amount of volume necessary to dissi-
pate the heat generated by the drive. We either dissipate heat
through a heatsinking device (similar to an aluminum back
plane), or by letting it flow out to the “ambient” air. If there is
sufficient aluminum in the enclosure’s back plane, then the
internal volume may be smaller.
However, if using a plastic or steel enclosure, where little or no
backplane exists to dissipate heat from the drive, then you will
need to use forced air ventilation, or a larger volume inside the
enclosure to dissipate the heat into the “ambient” air.
Most enclosure manufacturers use computers to quickly answer
your questions and recommend the correct size enclosure for
your drive.
All Minarik’s SCR drives require at least 1” of clearance at the
top point of the drive. Filtered PWM drives (due to bus capaci-
tors) require at least 2” clearance from the top. When mount-
ing anything into the lid, remember to make accommodations
in the depth behind the lid for components like switches and
potentiometers.
Unfiltered SCR drives are typically 96% efficient, while filtered
PWM drives are typically 94% efficient. We calculate the heat
dissipation by multiplying the power output to the motor mea-
sured in watts (1 Hp motor at full load = 746 watts) by the inef-
ficiency of the drive (1-h) = .04 for SCR drive, (1-h) = .06 for
PWM drives).
Conversion Factors & NEMA Ratings
Inertia Conversion Factors
lb-ft
2
x 144 = lb-in
2
oz-in
2
x 0.0625 = lb-in
2
lb-ft-sec
2
x 4600 = lb-in
2
oz-in-sec
2
x 24 = lb-in
2
gm=cm
2
x .000342 = lb-in
2
kp-m-sec
2
x 33,500 = lb-in
2
Metric-Decimal Equivalents
1 inch = 2.54 cm
1 cm = 0.3937 inch
1 pond (gm) = 0.03527 oz
1 oz = 28.35 pond(gm)
1 kp (kg) = 2.205 pound
1 gm-cm = 0.0139 oz.in
1 kg-cm = 1 kp-cm=13.9 oz-in
1 hp = 746 watts
°F = (°C x 9/5) + 32
°C = (°F - 32) x 5/9
Standard
NEMA (IEC)*
NEMA 1 (IP10) 844
NEMA 3 (IP54) 88444 4 44
NEMA 4 (IP56) 884444444
NEMA 4X (IP56) 884444444 4
NEMA 12 (IP52) 84444 4
NEMA 13 (IP54) 84444 44
Indoors
Outdoors
Accidental bodily contact Falling dirt
Dust, lint, fibers (non-volatile) Windblown dust Falling liquid, light splash Indirect hosedown & heavy splash
Rain, snow & sleet
Oil or coolant seepage Oil or coolant spray & splash Corrosive agents
Intended
Use
Provides protection against:
1st Protection against 2nd Protection
Digit foreign objects Digit against moisture
0 Not protected 0 Not protected
1 Protected against 1 Protected against
objects >50mm dripping water
2 Protected against 2 Protected against dripping
objects > 12mm water when tilted up to 15N
3 Protected against 3 Protected against
objects > 2.5mm spraying water
4 Protected against 4 Protected against
objects > 1.0mm splashing water
5 Dust protected 5 Protected against water jets
6 Dust tight 6 Protected against
heavy seas
---------- 7 Protection against the
effects of immersion
---------- 8 Protection against submersion
Depth
Heat Dissipation
EXAMPLE MARKING: IP 68 would indicate a dusttight (1st digit 6) piece of equipment which
is protected against submersion in water (2nd digit 8)
*The IEC equivalents listed in this column are approximate: NEMA types meet or exceed the
test requirements for the associated IEC classifications.
UNITS for ELECTRICAL SPECIFICATIONS
SIZING an ENCLOSURE
ENCLOSURE STANDARDS
INGRESS PROTECTION (IP) CODES
for Nonhazardous Locations
Unit Symbol Physical Quantity
ampere A electrical current
farad F electrical capacitance
henry H inductance
meter m length
ohm electrical resistance
second s time
volt V electrical potential difference
watt W power
form factor ff rms current ÷ avg current
1 01
Call us toll free 1•800•MINARIK or download manuals at www.minarikdrives.com
K
REFERENCE