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Power Resistors

These are used with AC variable frequency drives to produce a braking torque in the motor during overhauling load conditions. In addition the dynamic braking resistor prevents the flow of current from reaching the current inverter and causing equipment damage. They are double insulated and rated at 1200 volts. The resistance value in ohms determines the amount of braking torque produced, and thus the rate at which the motor will stop. The resistor wattage is sized to prevent overheating during normal braking cycles.

Dynamic braking resistors are often added to prevent over-voltage trips on the drive when stopping the motor.

I-Gard dynamic braking (DB) resistors are designed to prevent an over-voltage trip while slowing a high inertia load, through the use of alternating current (AC) variable speed drives. The dynamic braking resistor is connected across the direct current (DC) bus and can see voltages as high as 1000 volts DC. The resistance value in Ohms determines the amount of braking torque produced and thus the rate at which the motor will stop. This value must be within acceptable limits for the particular drive and application.

The resistor wattage is sized to prevent overheating during normal braking cycles. Heavy duty applications require larger (higher wattage rated) resistors. Under braking conditions, the DB resistors operate at an elevated DC voltage up to 1000 Volts DC at times. To meet this unusual and demanding requirement I-Gard has re-engineered every component in the assembly.

Dynamic braking resistors are often added to prevent over-voltage trips on the drive when stopping the motor.

Benefits of Dynamic Braking Resistors

  • Prevent over-voltage trip.
  • Prevent overheating during normal braking cycles.
  • Ideal for electric motors in systems such as trains, elevators, construction cranes, etc.
  • Enclosures feature a built-in junction box with conduit knockouts for easy wiring.
  • All electrical components rated and tested to 1000V DV to ensure safe operations under all conditions.
  • Stainless steel jumpers and terminal hardware reduce replacement costs.
  • CSA approved (file C22.2 No.14). Products not manufactured and designed around CSA standard may well be under-rated, under designed and lack the necessary safety features.

Thicker, stronger enclosure to provide the strength and rigidity necessary to resist abuse without compromising performance.

These resistors are used to control motor starting and stopping anywhere from reduced voltage motors of low horsepower up to large motor applications such as materials handling, mine hoists, cranes etc.

The most common applications are:

  • AC wound rotor induction motors– where the resistor is wired into the motor secondary slip rings and provides a soft start as resistance is removed in steps.
  • AC squirrel cage motors – where the resistor is used as a ballast for soft starting also known as reduced voltage starting.
  • DC series wound motors – where the current limiting resistor is wired to the field to control motor current, since torque is directly proportional to current, for starting and stopping.

These resistors are used to control motor starting and stopping anywhere from reduced voltage motors of low horsepower up to large motor applications such as materials handling, mine hoists, cranes etc.

The most common applications are:

  • AC wound rotor induction motors – where the resistor is wired into the motor secondary slip rings and provides a soft start as resistance is removed in steps.
  • AC squirrel cage motors – where the resistor is used as a ballast for soft starting also known as reduced voltage starting.

DC series wound motors – where the current limiting resistor is wired to the field to control motor current, since torque is directly proportional to current, for starting and stopping.

I-Gard’s range of resistive load banks have three main applications:

  • Testing AC and DC systems, including batteries, uninterruptible power supplies and standby generators.
  • Load stabilization – acting as a load source to minimize power swings.
  • Load simulation – used in aerospace and other applications to simulate load requirements on a system.

I-Gard’s range of resistive load banks have three main applications:

Testing AC and DC systems, including batteries, uninterruptible power supplies and standby generators.

Load stabilization – acting as a load source to minimize power swings.
Load simulation – used in aerospace and other applications to simulate load requirements on a system.

I-Gard capabilities include specialized high precision automated load banks, remotely or PLC controlled load banks and high voltage and high current designs that satisfy even the most stringent project requirements. Our sales team would be please to work with you in evaluating the best design available.

We offer a wide range from single, low wattage, high resistance elements, to large, multi-element, 150kW banks.

Our in-house, skilled engineering allows precision designs, including challenging or special requirements such as low inductance designs, and impulse withstand and testing.

I-Gard is the leading manufacturer of custom resistor assemblies for harmonic resistor banks, offering a wide range from single, low wattage, high-resistance elements, to large, multi-element, 150kW banks. Our in-house, skilled engineering allows precision designs, including challenging or special requirements such as low inductance designs, and impulse withstand and testing. All products are produced within I-Gard’s certified ISO 9001 quality assurance program. Our wide range of resistor components provides the flexibility to manufacture a wide range of harmonic filter resistors to suit your requirements

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