The three-limb iron core is made of oblique cut Grain-oriented, seven-step silicon steel laminations insulated on both sides, guaranteeing low losses and low noise. These values are even improved by laser treatment. It is protected on the surface with a flash-proof varnish in order to prevent the sheet from corrosion and to reduce the noise.
The winding as the centerpiece of the transformer must be especially protected – both against high electrical stress due to external over voltages and against mechanical overloads by short circuits. Huarui transformers are systematically designed to meet these requirements. The windings are made of copper or aluminum. Low-voltage windings are made of strip or flat wire, and the high voltage windings are manufactured from round or profile wire. (“diamond-dotted paper”) bonds the winding into a compact block while drying and increases the short-circuit capacity additionally.
The Tank Whether during transport or operation –the tank must be absolutely tight under mechanical stress. Preconditions to achieve this are constructional experience, the most modern calculation methods and high-quality welding work. Special attention is paid to corrosion protection. Pretreatment of the surface is processed by phosphating pickling, contributes to corrosion protection, just like multi-coating with preset drying times for each layer. On request, hot-dip galvanization provides for even better protection.
For each transformer are prepared and issued a test report, in accordance with IEC 60076. except for routine tests, we also offer type tests and specialised tests to meet all customer requirements. We make what matters work for our customers in a safe and reliable way.
a) Measurement of winding resistance
b) Measurement of voltage ratio and check of phase displacement
c) Measurement of short-circuit impedance and loss
d) Measurement of no-load loss and current
e) Dielectric routine tests
f) Tests on on-load tap-changers, where appropriate
g) Leak testing with pressure for liquid-immersed transformers(tightness test)
h) Tightness tests and pressure tests for tanks for gas-filled transformers
i) Check of the ratio and polarity of built-in current transformers
j) Check of core and frame insulation for liquid immersed transformers with core or frame insulation
a) Temperature-rise type test
b) Dielectric type tests
c) Determination of sound level for each method of cooling for which a guaranteed sound level is specified
d) Measurement of the power taken by the fan and liquid pump motors
e) Measurement of no-load loss and current at 90% and 110% of fated voltage
Varelen Electric Co., Ltd