Electric drives of ПЧВС series

 
Application

Thyristor electric drives based on the AC converter-fed motor circuit are designed for regu lation of the rotation frequency of mechanisms driven by synchronous motors with voltages of 6kV, 10kV and capacity from 1.6 to 20 MW.

There is positive experience of long-term exploitation of the electric drive in different branches of industry: mechanisms with fan characteristic of the load torque (chargers, smoke exhausters, air blowers, centrifugal pumps,

 compressors etc.) that require rotation frequency regulation for metallurgy, oil, gas, cement, metal mining, chemical industries; static starters for frequency start with limitation of starting current and precise automatic synchronization with the supply of large synchronous machines (turbo- and hydro-generators, reversible units of pumped storage stations).

 

 
Structure
 
ПЧВС electric drive includes input and, if required, output current-limiting reactors, smoothing reactors, rectifier power board, inverter power board, control cabinet, controlled exciter. Maximum overall setting dimensions of boards and smoothing reactors are indicated in the table. ПЧВС electric drives are designed for operation in areas with moderate and cold climate (climatic version – УХЛ4) at temperature from +1ºC to +40ºC, with relative humidity of no more than 80% at temperature of +25ºC, and in areas with tropical climate (climatic version 04).
The climatic version and placement category of smoothing reactors is УХЛ2. Current-limiting reactors are for indoor installation.
The power part of ПЧВС is based on thyristors of the class 60. Cooling is air, forced.
Elements of the control system of ПЧВС electric drives are structurally placed at circuit plates in the control cabinet with the same dimensions (800*600*2200mm) for all versions. A controlled exciter for the current up to 320A of one-cabinet design with dimensions of 600*800*2355mm and a matching transformer are delivered in the package.
Rotation frequency of a synchronous motor is determined by the value of the output frequency of a thyristor frequency converter; the frequency rated value is 50/60Hz. The range of frequency adjustment is 3Hz – 50/60Hz.
The efficiency coefficient of the electric drive in the nominal mode is no less than 0.97.
The electric drive capacity coefficient (cos φ) with the rated voltage of the circuit feeder and the rated voltage at clamps of a synchronous motor is no less than 0.9.
 
ПЧВС electric drives provide:
  • smooth frequency start of a drive synchronous motor;
  • adjustment of the rotation frequency of a drive motor in the range of 1:10;
  • continuous operation with the steady rotation frequency within the limits of the mentioned adjustment range, stabilization of the set rotation frequency with the precision determined by a tachometric device (5% – without application of a tachometric device);
  • braking of a drive motor with energy recuperation;
  • repeated actuation of the electric drive when a motor is rotating within the working range of rotation frequencies at running-out;
  • precise automatic synchronization of a drive motor with the mains supply;
  • limitation of current and torque of a drive motor in steady and transient modes.
General technical characteristics of electric drives of ПЧВС series
Table 1.
Rated parameters
Power part dimensions
L*B*H, mm
Smoothing reactor
(type, dymensions, weight)
Q-ty
Current-limiting reactor
(type, dymensions, weight)
Mains voltage,
kV
Motor capacity,
MW
Rectified current,
A
6
2.0
250
 
 
СРОМ-1000, 250А,50mH, 2150*1500*2800, W=3.5t
2
РБ 10-630-0,56 630А
three-phase set
3.15
400
4800 x 800 x 2200
СРОМ-8000, 400А, 50mH, 1800*1800*3300,W=10t
1 (2)
6.3
800
 
СРОМ-16000, 800А,25mH, 2600*2100*4100,W=13.5t
1 (2)
10
3.15
250
 
СРОМ-1000, 250А,50mH, 2150*1500*2800, W=3.5t
2
5.0
400
6800 x 1000 x 2200
СРОМ-1000, 250А,50mH, 2150*1500*2800, W=3.5t
1 (2)
10.0
800
 
 
СРОМ-8000, 400А, 50mH, 1800*1800*3300,W=10t
1 (2)
 
*) an indoor dry-type reactor of РСС type can be applied as a smoothing reactor
**) a three-phase set of concrete reactors of РББ or РБ10 type can be applied as a current-limiting reactor
The functional diagram of the thyristor electric drive on the basis of the frequency converter of ПЧВС series is given in Figure 2.
The frequency converter (ПЧВС) is designed on the basis of AC converter-fed motor circuit and includes a high-voltage rectifier, grid-controlled inverter and smoothing inductor (ДС) in the direct current link. A drive motor is the inverter's load. The electromechanical system “inverter-motor” can be considered as an equivalent direct-current motor where mechanical commutation switch (collector) is replaced with an electric commutation switch (inverter). Such system has all the advantages of a direct current motor in terms of regulating characteristics and of a synchronous motor in terms of structural benefits.