Standard Ratings
Howard standard VPI transformers are suitable for operation in relatively clean environments and under "usual service conditions" as defined by IEEE Standard C57.12.01.
Power: 225-2,500 kVA three-phase, self-cooled AA-rated
High-voltage rating: 2.4 kV-34.5 kV
High-voltage BlL: up to 150 kV (per IEEE standards)
Low-voltage rating: 120 V?600 V
Low-voltage BlL: up to 30 kV (per IEEE standards)
Temperature rise at rated load: 150°C (at 30°C average/40°C maximum ambient)
Frequency: 60 Hz.
Standard Design Features and Accessories
220°C insulation system
Step-lap mitered core
Core ground strap (insulated core with single ground point)
Painted core
High-voltage taps (two 2-1/2% above and below nominal)
NEMA 1 enclosure
Lifting eyes
Provisions for rolling
Capability for adding cooling fans (units over 500 kVA)
Electrostatically-applied powder exterior finish with urethane top coat (ANSI 61 gray)
Ground pad
Diagrammatic nameplate (aluminum)
Standard Design Features and Accessories
220°C insulation system
Step-lap mitered core
Core ground strap (insulated core with single ground point)
Painted core
High-voltage taps (two 2-1/2% above and below nominal)
NEMA 1 enclosure
Lifting eyes
Provisions for rolling
Capability for adding cooling fans (units over 500 kVA)
Electrostatically-applied powder exterior finish with urethane top coat (ANSI 61 gray)
Ground pad
Diagrammatic nameplate (aluminum)
Optional Design Features and Accessories Howard excels at producing custom designs for non-standard applications and can offer numerous optional features and accessories to suit a customer's special requirements.
Custom designs for special applications
Loss optimization for lower total owning cost
Higher efficiency requirement
50 Hz. frequency
Non-standard ambient conditions
Non-standard BIL level
Non-standard altitude requirement
Non-standard sound requirement
Higher overload capacity
Low X/R ratios
K- factor rated (K-1, K-4, K-9)
Special seismic qualification
Reduced vibration and vibration isolation
Retrofit designs
80°C or 115°C temperature rise
Automatic fan cooling package (FA rated)
Digital temperature monitor
Copper bus and windings
Wye-wye connected windings
Special taps available
Provisions for parallel operation
Ground bus (copper)
Medium-voltage interrupter switch
Lightning arresters
R/C snubbers
Current transformers
Potential transformers (contact factory)
Power meter
Control power transformer
SCADA interface
Space heaters with thermostat
Flanged throats and air terminal chambers
Dust filters (for non-UL listed transformers)
Screens for insect and rodent proofing
Wheels
IR windows
ANSI 49 or ANSI 70 external gray finish
Stainless-steel enclosure
Stainless-steel diagrammatic nameplate |