Howard Mobile Power Transformers User Manual
Howard Industries, Inc.
ISO-9001 Certied
Introduction
Howard Industries Mobile Power
transformers are specially designed
for use with mobile power systems
and are the ideal choice for applications requiring step-up transformation
and interconnection with an electrical distribution grid. These rugged
transformers can take all the abuse
a transportable system typically
receives. They are specially designed
and equipped for the rental power
market, with many valuable features
that improve portability and increase
exibility for use with different grid
voltages.
Contact the factory or your local
Howard Industries representative for
more information about our Mobile
Power transformer line and about the
many custom solutions we can offer.
Ratings
Standard ratings for Mobile Power
transformers have been selected to
satisfy typical requirements for mobile
power systems. In addition to these
standard ratings, a wide range of
optional ratings is available to satisfy
any special customer requirement.
• Standard capacities: 45, 75, 112.5,
150, 225, 300, 500, 750, 1000,
1500, 2000, 2500, 3000, 3750,
and 5000 kVA
• Standard high-voltage rating:
14400 volts delta, with taps at
13800, 13200, 12870, 12470,
12000, and 11700 volts.
Optional high-voltage ratings from
2400 through 19920 volts
• Standard low-voltage rating:
480Y/277 volts.
Optional low-voltage ratings from
120 through 600 volts
• Standard frequency: 60 Hertz.
Optional frequency: 50 Hertz
Three-Phase Pad-Mounted
Mobile Power Transformers
FIGURE 1: Three-phase Mobile Power transformer
Standard Features
• Designed and manufactured in
accordance with all applicable
IEEE/ANSI and NEMA standards
• Non-loadbreak high-voltage tap
switch with operating handle
located in the high-voltage
compartment
• Externally clamped porcelain
high-voltage bushings with spade
terminals (live-front construction)
• Mounting provisions for lightning
arresters in the high-voltage
compartment
• Externally clamped epoxy or
porcelain low-voltage bushings
with integral spade terminals
• Removable neutral ground strap in
low-voltage compartment
• Lifting provisions
• Jacking and rolling provisions
• Removable steel forklift channels
Catolog Section
91-20
• Removable terminal compartment
and front sill
• Tamper resistant removable tank
access cover
• Three-point door latching system
with padlock provision and
recessed interlocking pentahead
security bolt
• Tank grounding provisions
• Welded mild steel tank construction
with mild steel terminating
compartment
• Mild steel barrier between high-voltage and low-voltage compartments
• Corrosion resistant hardware
• Recessed tank compartment
bottom
• Domed covers on tank and terminal
compartment
• Electrostatically applied powder
paint nish with polyurethane topcoat (ANSI 70 light gray)
Document No. 2.4.136
Revision: 0
Issued: December 2, 2011
Copyright © 2011 Howard Industries, Inc.
1
Howard Industries, Inc.
Laurel, MS 39440
www.howardtransformers.com
91-20
Mobile Power
• Oil ll/oil level plug
• Oil drain valve with sampling device
• Automatic pressure relief device
• Dial-type liquid level gauge
• Dial-type liquid temperature gauge
• Electrical grade mineral oil insulat-
ing uid with oxidation inhibitor
• Laser engraved nameplate
• Bushing designation labels
Optional Features
• Insulated interphase barriers
• Two 2.5% high-voltage taps above
and below normal voltage, or four
2.5% high-voltage taps below
normal voltage, or four 2.5% taps
above normal voltage, or no highvoltage taps
• Dual high-voltage rating with nonloadbreak switch handle located in
the high-voltage compartment (not
available in combination with highvoltage taps)
• High-voltage fuses, including
internal expulsion fuses, draw-out
expulsion fuses, internal backup
current limiting fuses, and draw-out
full-range current limiting fuses in
dry-well canisters
• Internal load-break high-voltage
ON/OFF switch with operating
handle located in the high-voltage
compartment
• Stainless steel tank and terminating compartment
• Flip-top hood on terminal
compartment
• Cover mounted high-capacity pressure relief device
• Rtemp®, silicone, or seed-based
vegetable oil insulating uid
• Cooling fans with control or fan
mounting provisions only
• Mounting provisions for external
electricity meter
• Hexhead security bolt (pentahead
standard)
• Temporary service access provision
(conduit hole) in terminal compartment sill
• Optional topcoat paint color: ANSI
49 light gray, ANSI 61 light gray,
ANSI 24 dark gray, olive green
(Munsell 7GY3.25/1.5), or white
• Tank grounding connectors
Unit Substation Designs
In addition to the standard padmounted compartmental design
previously described, Mobile
Power transformers can also be
supplied in a unit substation design
(Figure 2), available with a variety
of different high-voltage and lowvoltage termination interfaces, such
as full-height anges, throats, or air
terminal compartments. Substation
transformers are available in
capacities through 10,000 kVA, with
high-voltage ratings up to 69 kV.
Figure 2: Typical unit substation transformer.
Document No. 2.4.136
Revision: 0
Issued: December 2, 2011
Mobile Power Transformers
Catalog Section 91-20
Document 2.4.136, Revision 0, December 2, 2011
Copyright © 2011 Howard Industries, Inc.
Laurel, Mississippi
Telephone: 601-425-3151
Fax: 601-649-8090
E-mail: mkt@howard.com
Web: howardtransformers.com
Copyright © 2011 Howard Industries, Inc.
2
www.howardtransformers.com
Howard Industries, Inc.
Laurel, MS 39440
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