The magnetism conductor of core is the magnetic circuit of transformer. It changes the electric energy of primary circuit into magnetism can, can change the electric energy that is sub circuit by his magnetism again, it is the agency that energy changes. The weight of core is in transformer has absolutely advantage in each component, hold gross weight in common transformer 60% the left and right sides. The breed of core material basically has: Silicon steel piece, nickel of pure iron of the alloy that be not brilliant, electrician, iron (slope not) alloy, iron is aluminum-silicon alloy, soft magnetism ferrite. Transformer core basically uses silicon steel piece with the alloy that be not brilliant.

To transformer silicon steel piece the requirement is:

1. has the high magnetic field strength with guide magnetism rate is in particular to fall, magnetism conductance is taller, want to deliver magnetic flux waiting for a quantity, needs silicon steel piece less, the volume of core is minorrer, the weight of the product is lighter. Because bulk is reduced, but managing lead and the calorific loss that reduce lead resistor place to cause.

2. asks to be below certain frequency and magnetic flux density, have low iron damage, namely the silicon steel of unit weight piece the loss that causes (magnetic hysteresis loss and eddy current loss) want low, can reduce the total loss of transformer, improve the efficiency of transformer.

Core is the key of production transformer product. By transformer the formula of the principle is knowable

10-4 of · of Az of · of Bm of · of W1 of · of U1=4.44 · F, (V)

Reason U1

-- , 10-4 of · of Az of · of Bm of · of =4.44 · F, (V/ circles)

W1

With Likede

U1U2

Et= -- , = -- , 10-4 of · of Az of · of Bm of · of =4.44 · F, (V/ circles)

W1W2

Go up the Et in type, call every full electromotive force. By this type Bm of density of knowable magnetic flux basically was decided the basic function of transformer and material are used. In iron caustic (record loss for nothing) Bm of density of the magnetic flux when up to standard takes a cost big, et of every full electromotive force is changeless and core is significant cut area Az is small, core dosage is little; Core is significant cut area Az is changeless and Et of every full electromotive force takes a cost big, copper cash dosage is little; Somes Et of every full electromotive force is big and core is somes cut area Az is small more significant, cupreous iron all is saved;

Bm of magnetic flux density takes a cost small, et of every full electromotive force is changeless and core is significant cut area Az is big, core dosage is much; Core is significant cut area Az is changeless and Et of every full electromotive force takes a cost small, copper cash dosage is much; Somes Et of every full electromotive force is small and core is somes cut area Az is big more significant, cupreous iron all is expended;

From afore-mentioned analysises somes knowable Bm is big, copper of province iron, province or all save some, but Bm value is by electric steel piece the transformer function of the requirement that reach place (if cross excitation) decision Bm can be only inside certain limits.
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