Reparare, modernizare, generatoare de tranzistoare, generatoare de tuburi, triode, lămpi de generație

Repair and Modernization of Induction Lamp Generators HF

Lamp Generators

Lamp generators (the lamp is a triode) are devices used for surface heat treatment operating at a frequency range from 100 kHz to 4 MHz. However, the most commonly used industrial devices operate at a frequency of about 400 kHz. Modernization of lamp generators means replacing essential components of the device. The replacement of these components aims to repair or improve the device’s technical performance as well as achieve better technological results. Generators subject to modernization are most often devices designed and constructed by both domestic and foreign manufacturers in the 1950s, 1960s, 1970s, and 1980s. Lamp generators are currently often (due to the appearance of fast semiconductor switches on the market) replaced by transistor generators (with IGBT or MOSFET type transistors).

Advantages of Transistor Generators

Transistor generators have the following advantages:

• Higher efficiency by about 20% (transistor converter: 90%-95%, triode: 70%-75%).
• Lower and safer operating voltages (transistor generator: approx. 0.5 kV, lamp generator: approx. 10 kV).
• Cheaper transistor bridges despite the relatively high cost of the generation lamp. Limited lifespan of the triode, although with proper operation, i.e., efficient protections and effective water and air cooling systems, operation in two-shift mode is guaranteed even beyond 5 years.
• Very favorable in terms of operation for homogeneous heating in technological lines and in highly automated processes.

Advantages of Lamp Generators

Lamp generators have the following advantages:

• The generation lamp (triode) is resistant to all kinds of disturbances and overloads (in semiconductor generators transistor bridges most often fail. Their price is certainly much lower than the price of a triode, but this is not insignificant for operating costs).
• The lamp generator is a self-oscillating device and thus very universal, i.e., it easily starts and operates very well both under overload and underload conditions.
• The device does not require special tuning procedures when changing exciters or changing treated parts.
• It is very easy to heat parts with it both from the outside and from the inside, flat surfaces, as well as gear teeth.

Construction of a Lamp Generator

A lamp generator basically consists of two blocks:

• A high-voltage power supply with output voltage regulation from 0.5 kV to 10 kV.
• The actual generator circuit, most often operating in a self-oscillating Meissner, Hartley, or Colpitts type circuit.

Generator Modernization Process

Generator modernization should be considered in several aspects:

1. In the high-voltage power supply.
   • Replacing the thyratron regulator with a thyristor regulator.
     
     • Increases operator safety as control takes place at the mains voltage level, not the elevated voltage.
     • Significantly improves output power regulation accuracy and enables connection to modern control panels.
     • After installing circuits with increased sensitivity to overloads and other adverse operating conditions, the durability and lifespan of components improve.
   • Installation of a modern thyristor regulator.
     
     
     • Significantly improves output power regulation accuracy and enables connection to modern control panels and integration with the entire heat treatment process line.
2. In the generator circuit itself.
   • Replacement of the generation lamp no longer produced with a lamp easily available on the domestic market.
     
     
     • Previously used triodes were mostly domestically produced and placed in a special cooling jacket (or pot). Currently produced lamps have an integrated cooling system. This involves mechanical, hydraulic, and electrical modifications. The benefit is the availability on the domestic market of a wide range of triodes with integrated cooling.
   • Modernization of the resonant circuit
     
     
     • Modernization of the resonant circuit leads to increased electrical efficiency, reduced thermal losses (power) in the resonant circuit, and an increase in the device's output power by several to a dozen or so percent.

Performing the above-described modernization activities means that generators produced several decades ago can still be very useful for even technologically demanding heat treatment processes and with much lower financial expenditures than investing in modern transistor generators would require.

The company DACPOL offers comprehensive selection of replacements for no longer produced LAMINA lamps: T-25W, T-25P, T26W/22, T26W/23, T-26P/22, T-26P/23, T-10P/22, T-12W/21, T-60W/12, T-60W/22, T-60V/12. We select the replacement and provide a comprehensive lamp replacement service along with starting the generator on the replaced lamp.

The attached drawing shows the basic schematic diagram of the modernized GIS-10 type generator; after modernization, the generator was named GIS-10RT (RT – thyristor regulator). Numbers in circles 1, 3 indicate the high-current path of the high-voltage power supply. Number 4 indicates the actual induction generator block. Numbers 2, 5 indicate control, measurement, protection, and triode cathode power supply blocks. GIS-type generators were produced in the 1960s and early 1970s at WAREL plants and, after modernization, continue to operate successfully in small workplaces. Before modernization, power regulation was provided by a thyratron rectifier on the high-voltage transformer side 3TM1 (now replaced by a diode rectifier 3V1). Modernization involved removing the thyratron regulator and installing a thyristor regulator 2U1 with a control panel 2U2 and, on the high-voltage side, a diode rectifier (diode stacks) 3V1. If necessary, the resonant circuit 4V1, 4T3, 4T4, 4T2 is modernized.

Example Description of Performed Modernization

The modernization of the HFG/J40 type generator was carried out in 2017 at FAMUR S.A. – a company producing equipment for mining. The HFG/J40 generator was manufactured in 1962 by the Austrian company ELIN. Its operating frequency: 400 kHz, and the output power (guaranteed by the manufacturer) at the exciter terminals was 40 kW. In the early 1990s, the company ELCAL performed a modernization that involved replacing the BBC-produced triode with a domestically produced triode type T26W and replacing the thyratron regulator with a thyristor regulator type PRW 210/440 and diode rectifier stacks. In 2017, after about 25 years of operation, Dacpol Service undertook another modernization of the device. Below are selected photos showing the device before modernization.

The modernization included:

• Replacing the T26W lamp with a higher power lamp type RD35ZM available on the domestic market.
  - Replacing the lamp filament power supply circuit.
• Replacing the high-frequency output transformer with an air transformer of higher apparent power.
• Replacing the high-frequency filter (replacement of the high-frequency choke and addition of low-inductance high-frequency capacitors).
• Replacing the diode rectifier with a rectifier of higher current load and with overvoltage protection.
• Replacing the PRW 210/440 regulator with a modern RP3 type regulator.
• Replacing overload protections.
• Use of water-cooled high-frequency current cables.

After modernization, the generator’s output power increased by about 20%.

Below are selected photos showing the device after modernization.