Q1. What’s the advantage of CRGO core toroidal transformer?

The core of toroidal transformer is rolled by high-quality CRGO sheets (thickness <0.35mm), its performance is superior to laminated cores. The coils of toroidal transformer were wound on the core evenly, the direction of magnetic field lines generated by the coils almost completely coincides with the magnetic circuit of the core. Comparing laminated type toroidal transformer, its excitation energy & iron core loss will be reduced by 25%. Advantage including:

1). High electrical efficiency, no core gaps. The core stacking coefficient could >95%. Comparing to laminated core's magnetic permeability 1.2~1.4T only, the CRGO core magnetic permeability could reach to 1.5~1.8T, and the electrical efficiency as high as 95%. What's more, the carrying current only 10% of laminated type.

2). Comparing laminated core, the CRGO core with Smaller size, almost 50% weight lighter. Once keep the same cross-sectional area of the core, the toroidal transformer can change the core dimension easily to meet customers requirements.

3). The core without air gap, and the winding wound evenly, guarantee small magnetic leakage & low electromagnetic radiation. Even without additional shielding, it can be used in high-sensitivity electronic equipment, such as medical equipment.

4). No air gap can make less vibration & noise.

Q2: Which two of the three-wire power transformer are live wires?

A. For single group input/output toroidal transformer, generally two-line in and two-line out. While for three-line input lines is a dual-input transformer, request discuss accordingly:

1). Middle wire is 0 wire, others two is live wires, 220V-0V-220V as example, the input voltage can connect to (0-220V)220V or (220V-220V)440V.

2). the first line is 0 line, the last two are live lines, 0-220V-380V for example, it can be connected to (0-220V)220V, or(0-380V)380V.

Q3: For a power transformer, how to convert the W to VA?

A: For a power transformer, the VA is apparent power. In the formula calculation, 1VA = 1 Vol of voltage * 1 Ampere of current. It is treated as a power measure of direct current, and apparent power measure o alternating current. The apparent power including actual power and the conversion of energy per second in capacitance and inductance in the circuit( this part of energy does not do external work).

Watt (W): refer to electrical appliance's active power / actual power, that is, the energy consumed by the circuit per second.

The formula among them: W=VA* PF( PF is between 0 and 1)

Q4: What's the difference between toroidal transformer load and no-load conditions?

A: The difference including below:

Current: For load toroidal transformer, the primary & secondary have a certain load current. While, for no-load toroidal transformer, the primary is no-load excitation current, the secondary current is zero.

Voltage: For load toroidal transformer, the primary & secondary voltage is close to the rated value. While no-load is applied, no-load voltage with high value.

Temperature: Toroidal transformer with load temperature is higher than no-load ones.

Sounds: The electromagnetic sounds for toroidal transformer with load is higher than no-load transformer.

Q5: What's the characteristic of the transformer as the efficiency of the toroidal transformer varies with the output power?

A: While toroidal transformer's output power P2 is equal to the input power P1, the efficiency η is 100%, the transformer will not with any loss. But in fact, there is no such toroidal transformer in the market. Copper loss & iron loss are always generated while a toroidal transformer transmits electrical energy. Generally the higher power is, the smaller the loss & output power is, and then the higher the efficiency; the smaller power, the lower efficiency.

Q6: Toroidal transformers usually use UL1015 leads or UL1007 leads, what are their difference?

A: The conductor structure of the two is same, but the insulation thickness of wire and the outer diameter are difference, 1007 while is much thin than 1015. The main difference including withstand voltage & temperature. UL1015 leads withstand voltage is 600V, temperature resistance is 105°C, UL1007 leads withstand voltage is 300V, temperature resistance is 80°C.

Q7: Can the toroidal transformer primary be made of double windings?

A: Yes, no problem. Both primary and secondary could be customized into dual outputs. Could make input with three lines, two sets of input voltage such as 0-110V-220V with taps can share a 0V common line. Also can make input with four lines, independent winding type such as 110V 200V can be used, and insulation isolation is added between the two groups of input voltages to separate the windings.

Q8: How much W is equivalent to 100VA of a low frequency transformer?

A: Power units VA and W are two concepts, VA is the unit of apparent power, including active power and reactive power. W is the unit of active power. While output power factor is 1, the reactive power is zero, the apparent power is equal to the active power, under such condition, we could say 100VA is equal to 100W.

Q9: How to install the toroidal transformer?

A: Toroidal transformer including fully waterproof type, rainproof type and indoor type, different type with different installation way. The waterproof type toroidal transformer with mounting holes on the shells, can install directly. The rainproof type toroidal transformers including vertical design and hanging design, the cases are different. Indoor type toroidal transformer with bolt, nut, iron cover, rubber pads, bottom plates, which can be fixed to the circuit board directly.

Q10: What's main parts of a low frequency transformer?

A: A low frequency transformer mainly made with core, polyester film, copper wires, input/output lead sires, high temperature tape, some will with protection devices such as temperature control protection, overload protection, short circuit protection. etc.

Q11: Why the toroidal transformer can't be overloaded for a long time?

Answer: 1. Within the allowable range, the toroidal transformer can be overloaded in a short time.

2. Within the allowable range, long-term overload will lead to excessive temperature rise, and the poor heat dissipation, which will affect transformer service life.

3.Once overload exceeds the allowable range, toroidal transformer will burn out directly.

Q12: For the AC toroidal transformer, how to connect the green & yellow ground wires?

A: Both connection are supported. When connected to the 220V ground wire, it's protective grounding. While connected to the casing, since the case is fixed on the ground or wall, it's equivalent to protective grounding.

Q13: If the toroidal transformer secondary voltage divided into positive and negative poles?

A:  Neither the primary nor the secondary voltage divided. Single-winding toroidal transformer input/output are two lines, one of them is a zero line and the other is a live line, which are independent, can be accessed directly. For multi-winding output voltage, please notice the lead color corresponding to each group of voltages marked on the label.

Q14: If a margin request for an isolation transformer capacity selection?

A: Yes, a reasonable margin left is request. Common toroidal transformer working efficiency about 90%, high-quality isolation transformer achieve 92%~93%. It's better that the transformer's load not exceed the working efficiency. While the transformer work overloading for a long time, it's easily damaged by overheating.

Q15: What’s the difference between a toroidal transformer and an EI transformer?

A: 1. Structure: EI transformers core is completed by E & I-type silicon steel sheets.

Toroidal transformer core is made by 1pc punched "O"-shaped silicon steel sheet;

2. Performance: EI transformers with complex structure, high production cost, serious magnetic flux leakage, low efficiency.

Toroidal transformers are more efficient, low noise. For a confirmed capacity, toroidal transformer's size & weight are halved; for a slightly larger capacity transformer, the temperature can be lowered.