Factory testing, Quality assurance – Howard Network Transformers User Manual

Page 4

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Copyright © 2010 Howard Industries, Inc.


Factory Testing

In addition to numerous quality inspections throughout

the manufacturing process, fi nal tests are conducted on

the completed network transformer to ensure proper func-

tion of all systems. All tests are conducted in accordance

with applicable industry standards. Test equipment is

state-of-the-art and capable of extremely accurate and

reliable test measurements, meeting all the industry loss

measurement standards. All test systems are calibrated

regularly according to industry standards. Calibration of

loss-measuring equipment is NIST traceable.

The following standard and optional production-line tests

are performed. Standard tests are performed on each

completed transformer. Optional tests are performed

upon customer request and at customer expense. Cus-

tomers may arrange to witness factory testing. All tests

will be made in accordance with the latest revisions of

IEEE C57.12.00 Standard General Requirements for

Liquid-Immersed Distribution, Power, and Regulating

Transformers and IEEE C57.12.90 Standard Test Code for

Liquid-Immersed Distribution, Power and Regulating Trans-

formers and Guide for Short Circuit Testing of Distribution
and Power Transformers.

Quality Assurance

Howard employees understand the importance of quality,

particularly as it relates to network transformer applica-

tions. Emphasis on quality begins at design and follows

throughout the manufacturing and delivery processes.

Only the highest quality components and materials are

used in Howard network transformers. Attention to detail

during manufacture, and careful inspection and testing

ensure that a high level of quality is maintained.

Howard’s quality management system is designed to

ensure that all of the company’s products and services

meet or exceed our customers’ requirements and is certi-

fi ed by DQS-UL as being compliant with ISO-9001:2008.

The ISO-9001:2008 standard covers design, manufactur-

ing, and servicing systems, and is the most stringent and

comprehensive standard in the internationally recognized

ISO-9000 series of quality standards.

Network Transformer


Howard Industries, Inc.

Laurel, MS 39440


Catalog Section 94-10

Network Transformers

Issued: April 9, 2010

Production-Line Tests





Winding resistance

Winding insulation resistance (Megger)


Polarity and phase relation

Insulation power factor

No-load losses and excitation current

Impedance voltage and load losses

Zero-phase sequence impedence


Temperature rise

Low frequency dielectric tests

Applied potential

Induced potential

Lightning impulse

Front-of-wave impulse

Audible sound level

Leak test

Partial discharge (RIV)

ANSI impulse test