NATIONAL ALUMINIUM COMPANY LIMITED - Rites

21. Suitable for parallel operation : Yes
4.8 VARIABLE VOLTAGE VARIABLE FREQUENCY DRIVE
Basic design particulars
All VVVF Converters shall have Digital Control Technology with vector less control. VVVF shall
communicate to basic automation system.
Type of connection
• Three phase frequency converters with rectification and inversion i.e. variable voltage and
variable frequency output with current source / voltage source (PWM) inverters.
• Line reactors for harmonic and noise suppression
• Suitable for 415 V , 3 phase ,50 Hz , 4wire neutral earthed system
Overload capacity
• 150% of the rated current for 1 minutes followi following ng 100% load & to meet the drive overload
capacity.
• Efficiency more than 95% at full load
• Suitable to withstand vibrations more than 0.59.
• Output frequency : 5-50 Hz (Constant torque)
50-100 Hz (Constant power)
• Ramp rate: Linear acceleration and dec deceleration eleration adjustable independently.
Power components
The main power components of the VVVF equipment shall have the following incoming AC
side:
• Matching input power transformer / reactor
• AC line surge suppression network.
• ACB/MCCB
• Line contactors
Converter –Inverter Inverter Equipment
• Thyristor converter bridge for AC/DC
• DC link circuit with reactor/capacitor
• Inverter bridge for DC/AC
• PLC to take care of interlocking and sequencing etc.
• Mimic panel where drive is HT
Load side
• Filter network
• Step-up up transformer, as required
• Isolator and over over-load relay for each motor.
By-pass Arrangement
Technical Specification:Sec-6, Electrical
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