KCB Series Thyristor Triggering Transformers
(KCB421/301A)

1.Characteristics:

• Totally-encapsulated printed circuit board being able to be directly welded and assembled;
• High capability of mechanical and environmental isolation, compact in structure, solid, vibration-proof, moisture-proof and flame-resistance;
• High dielectric strength between coils;
• Ratio can be changed by customers to meet the requirement for triggering;
• Able to match thyristors of all capacities;
• Able to be used as common pulse transformers

2.Applications

The triggering transformer is used with thyristor. It is commonly connected in between controlled triggering unit and controlling grid of thyristor to transfer triggering pulse in thyristor equipment; and acts as a reliable isolator between high and low voltages. KCB Series triggering transformers can be used for the following equipment:

1. Voltage and speed controlled equipment;
2. Electric welding machine;
3. Elevator;
4. Power supply with intermediate frequency;
5. Rectifier;
6. Inverter frequency converter;
7. Self-controlled device;
8. Other thyristor device.

Typical circuit in application is showed in the following Diagram:

Notes:

1. R1 and D1 act as current continuing components.
   D1 normally is 1N4007,R1 is selected between 1K Ω ~ 2K Ω
2. D2,D3,R2 act as shaping components.
   D2,D3 can be 1N4007,R2 is optional from a few tens ohms to several hundreds
   ohms.

3.Typical specifications of models are listed in the following table.

4.Guide for use:

1) First of all, the needed dielectric strength Vp is determined according to the system's working voltage V₀ (effective value). It can be selected with the recommended values listed in Table 1:

Working Voltage V0	220V	380V	500V	800V	1100V
Dielectricity Strength Vp	1.9KV	3.1KV	4.5KV	6KV	8.3KV

2) The model can be selected in accordance with product of volt-microsecond ( udt ) and frequency of triggering pulse. There is a rule for the selection, which is referred to that the known product of volt-microsecond of triggering pulse should be equal to or less than the rated that of KCB triggering transformers in related range of frequencies;

(a). For users who use single pulse of 50HZ as triggering signal: the type can be determined with the known product of volt-microsecond by following the rule mentioned above.
For example, if it is known that the triggering pulse voltage is 8V, the pulse width is 250μs, the product of volt-microsecond then is 2000μVs( udt=8x250=2000μVs), the KCB-05 should be selected.

(b). For users who use pulse train (modulated pulse) as triggering signal: the selection should be made according to the parameters of modulated pulse.
For example, if it is known that the frequency of modulated pulse is 7KHz, the pulse amplitude is 10V, the product of volt-microsecond is then 800μVs (∫ udt=10x80=800μVs), the KCB-04 should be selected when fp =7KHz.

(c). For users who don’t know the parameters of triggering pulse: recommended model can be chosen from the table 2 as follows.

Thyristor capacity(A)	1-30	30-90	100-500	500-1000
Recommended Model	KCB-02	KCB472/104B KCB472/065B KCB472/951A	KCB-04 KCB674/864A KCB6743A KCB-0025 KCB-01	KCB418/311B KCB419/301A KCB674/211B KCB-05 KCB-06

Note: Recommended model is only for reference. A triggering transformer with the bigger ∫udt
should be selected as a general rule to make allowance.

5.Triggering Pulse Mode

(1). Single Pulse:

(2). Pulse Train:

6. Outline, Installation Dimension, Coil Diagram and Detailed Technical Parameters

Instructions:

1) The parameters in the following tables are the typical values given at room
temperature.

2) The meaning of the parameters:

u - transformer ratio = I : II : III : IV

Vp - effective voltage value of testing dielectric strength imposed on between coils, its duration is 60 seconds.

Fp - testing pulse frequency (Tp: cycle time).100Hz is referred to single pulse, the others referred to pulse train, assuming that width of pulse train (equivalent width) is td=2ms

∫udt - rated product of volt-microsecond V1·tn , which basically dose not change in certain range of frequencies

V₁-input pulse amplitude (primary pulse voltage)

tn - rated pulse width transferred under the related V1 and fp

V₂ - output pulse amplitude (secondary pulse voltage)