User Manual

Copyright © 2011 Howard Industries, Inc.
Howard Industries, Inc.
Laurel, MS 39440
www.howardtransformers.com
Document No. 2.4.136
Revision: 0
Issued: December 2, 2011
1
Introduction
Howard Industries Mobile Power
transformers are specially designed
for use with mobile power systems
and are the ideal choice for applica-
tions requiring step-up transformation
and interconnection with an electri-
cal 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
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
• 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-volt-
age 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 top-
coat (ANSI 70 light gray)
Mobile Power Transformers
Three-Phase Pad-Mounted
91-20
Catolog Section
Howard Industries, Inc.
ISO-9001 Certied
FIGURE 1: Three-phase Mobile Power transformer