Upgraded drive for DS-3A at Karmanovskaya State District Power Plant

Karmanovskaya GRES is the most powerful condensing thermal power plant in Bashkortostan, part of Bashkir Generating Company LLC. It is located in the north-west of the region, in the city of Neftekamsk, on the Buy River. It was designed and built to use local high-sulfur oil as fuel. Now the main fuel at Karmanovskaya GRES is natural gas.

The power plant consists of six blocks, each of which consists of steam boiler Pp-950-255GM with a capacity of 950 tons of steam per hour and turbine unit K-300-240 with a power of 300 MW. Commissioning one unit with a capacity of 300 MW annually, the power plant in 1973 became the most powerful in the republic. The installed electrical capacity of the station is currently 1,800 MW, and the thermal capacity is 204 Gcal/h.

Fig. 1 Karmanovskaya GRES

As part of the investment development program for 2016 at Karmanovskaya GRES, a decision was made to replace the obsolete and exhausted electric motor of the DAZO-1910-12 smoke exhauster (1700 kW, 500 rpm, 6 kV).

The specialists of ZAO EnergoFront were tasked with finding the best option for replacing the DAZO-1910-12 electric motor with a modern analogue, while at the request of the station, the new electric motor should be mounted on the existing foundation, without replacing the cable.

After a thorough analysis of the options, together with representatives of the Karmanovskaya GRES, it was decided to choose the ADO-1700-6000-12U1 electric motor (1700 kW, 500 rpm, 6 kV, with an adapter plate for installation on the existing foundation DAZO-1910-12) (Fig. 2) produced by NPO ELSIB PJSC.

Fig. 2 Dimensional characteristics of the electric motor ADO-1700-6000-12U1 manufactured by NPO "ELSIB" PJSC

Since 1953, NPO "ELSIB" PJSC has been known as a developer and manufacturer of large high-voltage asynchronous motors for the needs of energy, oil pumping, coal mining and other industries. Over the years, more than 60 thousand large electric motors have been produced.

Motors of the ADO series are asynchronous squirrel-cage motors with air-to-air cooling, designed to drive draft and mill equipment of thermal power plants. These are smoke exhausters and fans, hammer and ball mills, coal crushers and other mechanisms that impose a number of serious requirements on drive motors:

- reliable start-up of mechanisms with a large moment of inertia and a high moment of resistance when the voltage decreases during the start-up process to 0.8 Un;

- reliable operation under overloads up to 150-200%;

- long-term stable operation with increased vibrations from unbalanced mill rotors.

The engines are made with deep-slotted rotors and good contact between the rods and the iron of the tooth, which makes it possible to reduce the heating of the rods during starts and guarantee reliable operation of the engines with the number of starts over the service life of at least 5,000 for especially severe starting conditions and up to 10,000 for draft equipment. These operating conditions in starting modes are confirmed by both calculated data and real experience in operating electric motors at existing power plants.

Figure 3. Electric motor ADO-1700-6000-12U1

The proposed electric motor ADO-1700-6000-12U1 (Fig. 3) has a number of advantages over the existing electric motor DAZO-1910-12, namely:

- the ADO motor has a higher efficiency (the efficiency of the ADO electric motor is 95.9%, that of the DAZO electric motor is 94%), i.e., high energy efficiency, which allows saving the consumption of active electrical energy and, as a result, saving costs for the station’s own needs;

- in ADO electric motors manufactured by NPO "ELSIB" PJSC, reinforced stator winding insulation of the "Monolit-4" type on thermosetting binders is used, providing increased moisture resistance, mechanical (the monolithic stator core has increased rigidity) and electrical strength. As a result of using this technology, the service life of the electric motor increases by 50% and ranges from 30 years;

- the electric motor produced by NPO "ELSIB" PJSC has a temperature reserve for heating the electric motor stator - F when operating in class B;

- the weight of the ADO-1700-6000-12U1 electric motor is 3.5 tons less than the DAZO-1910-12 electric motor, as a result the static and dynamic load on the foundation will be reduced;

- high degree of protection IP54 of the ELSIB electric motor is more reliable and allows the electric motor to be operated in difficult conditions;

- shield layout of the ADO electric motor, mating of housing-shields-bearing assemblies by sharpening, significantly reduces the likelihood of the rotor and stator touching;

Analysis of the presented data confirms that the ADO-1700-6000-12U1 electric motor is the best solution for replacing the outdated DAZO-1910-12 electric motor.

Fig. 4 Existing electric motor DAZO-1910-12

To ensure strict compliance of the developed option for attaching the engine through the adapter plate to the actual structure of the foundation, specialists from the service department of JSC EnergoFront carried out an audit of the existing foundation (Fig. 4) at the station and collected initial data for the manufacture of the adapter plate and the electric motor itself.

After delivery of the equipment, specialists from the service department of JSC EnergoFront will provide a range of services for supervising installation and supervising adjustment of the electric motor.