Frequently Asked Question

Motor Control

Variable Frequency Drive

The energy saving is possible and is of significance only in the following case:

The Variable Frequency Drive is used for operating variable torque load like fans, blowers and pumps.

  • It is possible only if the fans, blowers and pumps are working at their partial capacity and not at full capacities.
  • It is of significance if Variable Frequency Drive is operating high power load i.e. beyond 20 HP, at low power loads like 1 to 20 HP the energy consumption is already less and is of less significance.
  • The energy saving is significant only if the connecting equipment works for considerable operating hours in a year.
  • The pressure drop created because of low RPM operation of fans, blowers and pumps should be tolerable to the system.

The energy saving in case of fans, blowers and pumps is possible to the extent of 30 to 60 % depending upon the operating point, no. of hrs. per year and the pressure drop tolerable to the system. In case of compressor the energy saving to the extent of 15 to 20 % is possible depending upon the loading - unloading cycle and operating hrs. per annum of the compressor.

The Variable Frequency Drive reduces the no load losses of the compressor motor by reducing the unloading time of operation. It reduces the pressure difference between high cutout pressure and low cut-in pressure by precise speed control of compressor motor and by using PID controller.

VT240S incorporates a regeneration power ride-through control and auto-restart function, so that it does not trip in case of an instantaneous power failure. Regeneration power ride-through control Continues operation during instantaneous power failure using regenerative energy. You can keep operating the motor without tripping in case of an instantaneous power failure by taking advantage of this function.

No, You cannot connect power factor improvement capacitors at the inverter's input or output end. Output capacitors can generate high currents containing high frequency components, resulting in the inverter tripping because of over current. This can also have adverse effects on the capacitors. To improve the power factor, insert an input AC reactor (optional) on the inverter's input side.

We can connect brake motor's circuit to the inverter's power supply side because if the braking circuit is directly connected to the inverter's output terminals, the brake cannot be released because of the lowered starting voltage.

Multi-pump control refers to operating up to six pumps (one variable speed control pump, and up to five ON/OFF control pumps) in parallel using five relay outputs provided in the inside of one VT240S. The pressure in the glow passage is controlled to be constant. The pressure step of the ON/OFF controlled pumps is interpolated by a pump which is controlled by the VT240S Variable Frequency Drive, which has the PID control function. This maintains the pressure's continuation. The relay output used for the pump's ON/OFF control are the VT240S standard relay output and the relay interface option relay output.

Reduced continuous over loads are provided to reduce maintenance and ensure motor operational life time is maximized. VFDs have pre configured over loads to account for many different motor types including 40:1 speed range variable torque loads, 100:1 speed range constant torque loads and non-conventional motors such as permanent magnet motors.

The ideal solution often involves using both AC and DC reactors in the VFD system to balance protection against voltage transients, harmonic reduction, and operational efficiency. This approach offers a comprehensive solution to power quality issues in VFD applications.

Ensure the motor is suitable for inverter duty, capable of handling the VFD's output without issues like overheating due to harmonic-rich currents. Motors should have isolated bearings and adequate heat dissipation.

Thoroughly assess environmental conditions such as temperature, humidity, and potential contaminants (dirt, dust, moisture). Ensure the VFD enclosure meets IP/NEMA standards for protection against these elements.

  • Open-loop V/Hz control: Adjusts voltage and frequency based solely on an external speed command without feedback.
  • Closed-loop V/Hz control: Incorporates encoder feedback to measure actual motor speed, comparing it with the commanded speed to adjust frequency accurately. This improves speed regulation but increases system complexity.

V/Hz control is cost-effective and straightforward, making it the most commonly used VFD control scheme. It supports both constant torque and variable torque applications and can deliver high torque (up to 150% at zero speed) for starting and peak loads.

Automation

Process-PLC

The process PLC combines all the characteristics of digital automation along with the digital I/O, analog I/O, PID loops, servo axes, stepper axes, MMI, HMI, networking, data handling and storage with one common programming platform.

Process PLC works on the principle of parallel multitasking, where the scan time is not dependent on the length of program as observed in case of cyclic program. Hence the higher priority functions can be assigned with top priority task, where the scan time can be considered as almost nil (in 2 to 3 milliseconds due to the capacitance effect of the input channel).

The all functionality of Process PLC like PID, Servo, Stepper, analog I/O, digital I/O, networking, MMI, HMI, interpolation etc can be achieved by one common program SYMPAS only. Hence the interfacing between different software is not required and all the functions can be achieved with real time control basis without any complexity. Chances of interface error are eliminated. Because of this, SYMPAS is called the interface free program

In today's automation industry, many controllers are available having different programming techniques like ladder, statement list, functional charts and plain text. In conventional plain text, the program is based on C or C ++. Hence the complexity of higher-level language is there, which requires special skill and experience of higher level language. However in SYMPAS, all the functionality of higher-level language is there, having plain English basic 26 commands for programming. Which do not require any experience of programming, even worker can also program the PLC within short course of time.

In conventional controllers, the program runs in cyclic mode. However the SYMPAS run in multitasking, where the total program split at different loops / sub programs/ tasks, which run parallel on time shared basis. In multitasking where the program is waiting for any events or condition true, the program will not run further till the condition is fulfilled and will not consume the time of CPU. Hence the CPU can efficiently perform the logic compared to cyclic program. Scan time of controller is much lesser and not dependent on length of program compared to conventional controllers.

  • VIADUKT : DOS based process monitoring software with graphic editor, menu structure, dynamics, trend graph, bar graph, message editor, data storage and DA transfer etc.
  • JETLINK : Windows NT based software with SCADA facility having full capacity of process monitoring .
  • JET WEB : Web based process monitoring software with Ethernet bus technology.

Yes, Linear and circular interpolation is available with Delta models.

Yes, They are fully protected from over voltage, over temperature, short-ckt, overload

Yes, The inherent design of the PLC is capable enough to absorb the noise generated in industry. All the products are CE approved and fully tested for such heavy electromagnetic noise. The housing is made from metal and the inter-bus communication is CAN bus.

50 years

Power Quality

Active Harmonic Filter

Active Harmonic Filter senses the load current in totality and generates the ideal reference current. By comparing this reference current with actual non-linear load current the Active Harmonic Filter finds out the harmonic current in the load. The Active Harmonic Filter generates equal and opposite harmonic current and cancels it. Thus the current drawn from source is distortion free sine wave current.

Active Harmonic Filter can improve the power factor to unity; it can also balance the 3-phase currents in case of any un-balance.

  • Active Harmonic Filter analyses the load by itself and one need not know the harmonic in the load as in case of passive harmonic filter.
  • Active Harmonic Filter is immune to the main frequency variation where as the passive harmonic filter is very much sensitive to the frequency of the mains power.
  • Active Harmonic Filter can take care of the changes in the non linearity of the load current where as Passive Harmonic Filter can't take care of the changes in the load current pattern.
  • Active Harmonic Filter can filter the harmonics up to 31st harmonic. The Passive Harmonic Filter is very difficult to tune as the harmonics beyond 11th. And it is ineffective in case of harmonics beyond 11th harmonic.

Using PWM control, the inverter generates noise that may affect nearby instrumentation and electronic equipment. Noise is classified by propagation route into: transmission noise, induction noise. Measures should be taken according to the types of noise. Take the following counter measures for noise, which affects other equipment.

  • Separate the signal cables from the power cables with sufficient distance.
  • Install noise filters.
  • Use twisted-pair shielding cables for weak electric circuits and signal circuits, and be sure to ground one end of the shielding.
  • Install the inverters separately from other equipment.
  • Cover the inverters and their cables with metal conduit tubes and metal control panels, and ground these covers.

By reducing harmonics, businesses can achieve improved equipment reliability, reduced downtime due to equipment failures, lower energy costs, compliance with regulatory standards, and enhanced overall operational efficiency.

Properly sizing the neutral wiring ensures it can handle the higher currents caused by harmonic distortion. Modern design practices often recommend sizing the neutral conductor to match or exceed the capacity of the phase conductors by about 50% in systems with significant non-linear loads.

Poor power quality can cause disruptions and downtime, leading to reduced productivity and operational inefficiencies. It forces equipment to operate less reliably and efficiently, affecting overall business performance.

Inefficient equipment due to poor power quality consumes more energy, contributing to higher greenhouse gas emissions. Improving power quality can enhance energy efficiency and reduce the environmental footprint of energy consumption.

Industries reliant on data processing and storage, such as IT and finance, depend on stable power to prevent data corruption or loss. Maintaining high power quality is crucial to ensuring data integrity and avoiding potentially severe consequences of power disturbances.

By selecting a specific tuned frequency that corresponds to the dominant harmonic, harmonic filters prevent resonance. Resonance occurs when the natural frequency of the filter coincides with harmonic frequencies present in the system, which can amplify voltage and current levels to dangerous levels.s

Consulting with a power quality expert or conducting a power quality analysis can help determine if tuned harmonic filters are necessary. Factors such as harmonic distortion levels, power factor requirements, and equipment sensitivity to harmonics should be evaluated.