Peripherals (VSD and Solar Drives)

VSD/Solar Drive installations might require or benefit from the use of some additional peripherals depending on the application (e.g., heavy industrial use, large motors, motor types etc.) and environment (quality of power source, interference of/with other applications, distance between VSD/Solar Drive and motor etc.) of the installation. These Peripherals, typically include items such as the following:

• DC Bus/Link Chokes/Reactors - Reactors for Power Factor Improvement
• AC Chokes/Reactors (Input and Output) - Reactors for Harmonic Filtration
• AC EMC/EMI Filters (Input and Output) - Filters for Noise Disturbance
• Sine Wave Filters
• Dynamic Braking Systems with:
  • Porcelain Braking Resistors/Windings; or
  • Aluminium Housed Braking Resistors

Besides the abovementioned, even though VSDs/Solar Drives include built-in Voltage Dependent Resistors (VDR) for suppressing surge voltage, the use of SPDs (Surge Protection Devices) are strongly recommended for all installations to protect the VSDs/Solar Drives from frequent surges, large Eskom power surges as well as lightning (although SPDs only provide protection to some degree). This is typically important for warranty and insurance claims that might arise from damages caused by lightning or power surges. Further to this, although VSDs/Solar Drives include a motor overload protection function, in circumstances where a single VSD/Solar Drive is used to drive two or more motors, Thermal Motor Protection Relays (Thermal Overload Relays - LRDs) are also recommended to prevent motor over-heating (installed between the VSD/Solar Drive and each motor). Also, if the rated capacity of the motor does not match that of the VSD/Solar Drive (especially when the VSD's /Solar Drive's rated power is greater than the motor's), it is advisable to adjust the motor protection parameters on the VSD/Solar Drive, or to install a thermal relay in the motor circuit for protection.

DC Chokes (Reactors for Power Factor Improvement)

Installation of DC Bus/Link Chokes/Reactors are highly recommended for applications from 250kW and larger (possibly from 90kW depending on circumstances). These units are connected after the input diode in the VSD/Solar Drive circuit (rectifier circuits) and are used to smooth the rectified current (improves the input current wave form distortion caused by the capacitor). This then:

• reduces the rectifier damage
• prevents capacitor overheating
• increases the power factor
• suppresses sudden changes in grid voltage (power supply)

TCGC offers the following DC Bus/Link Chokes/Reactors:

• EM-RAD2 (3-Phase ~220V)
• EM-RAD3 (3-Phase ~380V)
• EM-RAD5 (3-Phase ~525V)
• EM-RAD6 (3-Phase ~690V)

*Manufactured with Amp ratings according to specific requirement (Custom Voltage options also available on request).

*For installations where a DC Choke is required the VSD/Solar Drive wiring needs to be reconfigured by the manufacturer.

AC Chokes (Reactors for Harmonic Filtration)

The use of Line Reactors and Load Reactors increases the reliability, performance and efficiency of VSD/Solar Drive systems and extends the life of both the VSD/Solar Drive and motor.

Input Chokes (Line Reactors)

Connected in series with the incoming power supply line and is recommended when the power supply is unbalanced or when power factor is poor in order to:

• protect the VSD/Solar Drive from transient overvoltage conditions typically caused by utility capacitor switching;
• reduce the harmonic distortion and imbalance of the power supply current;
• reduce over-voltage trips caused by transient voltage spikes and power line surges;
• protect input rectifiers from in-rush current caused by sudden power supply surges and sags;
• extend the life of the DC bus capacitor bank by reducing the internal heating caused by ripple currents.

Output Chokes (Load Reactors)

Used for operating ‘non-VSD duty’ motors or when the length of wiring between the VSD/Solar Drive and motor exceeds 50 metres (can consider from 25 metres, but if more than 150m a SineWave Filter should be used instead of an Output Choke). This is to:

• protect the motor insulation against VSD/Solar Drive short circuits and IGBT reflective wave damage;
• allow the motor to run cooler by ‘smoothing’ the motor current waveform;
• reduce the effects of high motor wiring capacitance and ‘soften’ the dv/dt (high rates of change of voltage) applied to the motor windings;
• suppress the capacitive charging current of the cable between the VSD/Solar Drive and motor;
• protect motor windings.

TCGC offers the following AC Chokes/Reactors:

• Input Chokes (Line Reactors)
  • EM-RAI3 (3-Phase ~380V)
  • EM-RAI5 (3-Phase ~525V)
  • EM-RAI6 (3-Phase ~690V)
• Output Chokes (Load Reactors)
  • EM-RAO2 (3-Phase ~220V)
  • EM-RAO3 (3-Phase ~380V)
  • EM-RAO5 (3-Phase ~525V)
  • EM-RAO6 (3-Phase ~690V)

*Manufactured with Amp ratings according to specific requirement (Custom Voltage options available on request).

AC EMC/EMI Filters (For Noise Disturbance)

Some frequency-dependant electronic components can produce electric, magnetic or electromagnetic fields, which, if strong enough, can interfere with other appliances (cause undesired effects).  Electromagnetic Compatibility (EMC) is the ability of electrical equipment to operate without being affected by or causing Electromagnetic Interference (EMI).

Input Filters

Prevents EMI and radio interference which comes from the power supply cable to the VSD/Solar Drive. To be installed when other appliances cause interference on the VSD/Solar Drive supply line (power supply line).

Output Filters

Prevents EMI or radio interference which comes from the VSD/Solar Drive cable to the motor. To be installed when there is interference on the VSD/Solar Drive output line to the Motor (motor supply line).

TCGC offers the following AC EMC/EMI Filters for Noise Disturbance:

• Input Filters
  • EM-FIT3 (3-Phase ~380V)
  • EM-FIT5 (3-Phase ~525V)
  • EM-FIT6 (3-Phase ~690V)
• Output Filters
  • EM-FOT2 (3-Phase ~220V)
  • EM-FOT3 (3-Phase ~380V)
  • EM-FOT5 (3-Phase ~525V)
  • EM-FOT6 (3-Phase ~690V)

*Manufactured with Amp ratings according to specific requirement (Custom Voltage options available on request).

Sine Wave Filters

AC motors operate at their peak efficiency when they run on clean sinusoidal power. VSDs/Solar Drives produce square waves that are modulated so that the pulse width of the square waves can be varied continuously (known as pulse width modulation - PWM). VSDs/Solar Drives maintain fine control over the width and amplitude of the square waves so that they take on the appearance (as viewed on an oscilloscope) of good approximations of a sine wave. Yet, even the most sophisticated VSDs/Solar Drives fail to match the purity of a true sine wave. Installing a sine wave filter between the VSD/Solar Drive and the motor itself ‘smooths’ the VSD's/Solar Drive's PWM signal and converts it into a nearly perfect sinusoidal power wave form. This then:

• reduces motor insulation stress and eliminates switching acoustic noise from the motor;
• prevents disturbing pulses from being transmitted to the motor;
• minimises eddy current losses in the motor, resulting in a cooler motor and thus extended motor lifetime;
• reduces capacitances in screened motor supply cables which cause high oscillating circuit currents through motor bearings, vaporising lubricant, and causing damage to the bearings (especially in motors above 50 kW);
• provides protection for the VSD/Solar Drive (due to the lower pulse load being reflected in lower semiconductor losses).

To be installed for applications using older motors, applications in ‘aggressive’ environments, applications requiring frequent braking, 690V applications with general purpose motors and applications where cable lengths between the VSD/Solar Drive and motor is 150 to 500 metres (can reach 3000 metres).

TCGC offers the following Sine Wave Filters:

• EM-SWF2 (3-Phase ~220V)
• EM-SWF3 (3-Phase ~380V)
• EM-SWF5 (3-Phase ~525V)
• EM-SWF6 (3-Phase ~690V)

*Manufactured with Amp ratings according to specific requirement (Custom Voltage options available on request).

Dynamic Braking Systems

Generally used for industrial applications where quick stopping is required which could cause the DC bus voltage to rise (over voltage). It is thus required where the regenerated energy needs to be dissipated quickly to manage the DC bus voltage to prevent the VSD/Solar Drive from tripping.

These products are used to dissipate energy (cheap and simple method) by converting regenerative energy into thermal energy (burn off energy). Smaller VSDs/Solar Drives include a built-in switch to divert extra power to a resistor, but for larger units without a built-in braking switch, external braking units are required.

• These systems can release the energy regenerated during motor speed regulation (via brake resistance) to produce enough braking torque to ensure normal operation of the transducer and other devices.
• These systems are popular for use in cable/wire drawing machines, cranes, elevators, production machinery, mine hoists, centrifugal and oil pumps in oil field, etc.

TCGC offers the following Dynamic Braking Systems (listed according to VSD/Solar Drive kW Range):

• 1.5kW up to 22kW: No Break Unit Required (only require a resistor)
• EM-BU2: For 30~45kW Drives (Light Duty) - with matching resistor/s
• EM-BU3: For 55kW Drive (Light Duty) or 30~45kW Drives (Heavy Duty) - with matching resistor/s
• EM-BU3H: For 75kW Drive (Light Duty) or 55kW Drive (Heavy Duty) - with matching resistor/s
• EM-BU4H: For 90~132kW Drives (Light Duty) or 55kW Drive (Heavy Duty) or 2 units for Heavy Duty 160~200kW Drives - with matching resistor/s
• EM-BU5H: For 160~220kW Drives (Light Duty) or 90~132kW Drives (Heavy Duty) or 2 units for a Heavy Duty 220kW Drive - with matching resistor/s

TCGC offers Aluminium Housed Braking Resistors and Porcelain Windings (brake resistors)

*Custom Watt/Ohm resistor options available on request.