Power Resistors

Neutral Earthing Resistors / NERs

Neutral Earthing Resistors (NERs) are used to limit the fault current for safety of equipment and personnel in industrial systems.

In solid grounding, the system is directly grounded and the fault current is limited only by the soil resistance. The fault current can be very high and can damage the transformers, generators, motors, wiring and other equipments in the system. The NERs are inserted between neutral and ground in order to increase the net resistance in the event of an earth fault and limit the current to a safe level.

Technical Specifications
  • Operation Voltage : Up to 110 kV line to line systems

  • Rated Current : Up to 5000 A

  • Ambient Temperature : Up to 55oC

  • Resistance Alloy : Stainless-steel (CrNi or CrAl)

  • Protection Degree : IP 23 (outdoor) and others on demand

  • Standards : IEEE 32, IEC 60071-1 & 60071-2, IEC 60273, IEC 60137, IEC 60529, IEC 61869-2, IEC 61869-3, IEC 62271 series, IEC 60099-4, EN ISO 1461, EN 10346

High Resistance Earthing Systems

The design and operation of 240-5000 V systems, service continuity, personnel and equipment safety are the most important aspects in industrial systems. The use of the high-resistance grounded (HRG) system can provide a safe, reliable and economic system for 240-5000 V networks.

Features
  • 0-10 A analog ammeter, 0-250 V analog voltmeter with setting on panel

  • Automatic door switch for power shut down

  • Test button to indicate fault

  • Green light for normal conditions

  • Intermittent alarm and red light during ground fault

  • Pulse/Normal Selector swith to magnify current and intermittent pulse during ground fault

  • Auxiliary free contacts at pulse and alarm position during fault

  • Dimensions (LxWxH)= 60 x 60 x 180 cm (Other enclosure types avaible on demand)

  • Suitable for 240-5000 V three phase systems

  • Optional data logging

RC Snubber Filters

RC Snubber Filters consist of a capacitor and resistor connected in series across a switch which is controlling an inductive load.

For reactive power compensation, and mainly for voltage regulation purposes, shunt reactors are used at different voltage levels in the electric utility. During the turn-off action of the breaker or contactor of a shunt reactor, huge over-voltages are created due to the sudden interrupt of an inductive current. In order to prevent any damage to system equipment, voltage clampers, so called RC snubber filters are used in parallel with shunt reactors. They clamp the voltage overshoot due to the current interruption and damp out the oscillations safely.

Features
  • Longer insulation lifetime for machinery

  • Protects against insulation failures between windings

  • Protects against arcs between the contacts of vacuum circuit breakers and other switchgear due to high frequency over voltage

  • Protects against high frequency over voltage specifically caused by arc furnaces

  • Optional earth fault relay

Application Areas
  • Large motors

  • Generators

  • Induction and arc furnaces

  • Shunt reactors

  • Dry type transformers

Current Limiting Resistors

Current Limiting Resistors are designed for limiting the flow of current to some predetermined value and are used mainly to to keep flowing current within certain intervals while controlling the circuit.

Features
  • Stainless steel grid elements

  • Typically hot dip galvanized steel or stainless steel enclosure on demand

  • High thermal capacity to absorb high currents

  • Rugged-shock resistant construction

  • High Altitude ratings

  • Corrosion resistant nameplate

  • Specially designed units for hazardous and extreme locations

  • Designed and tested to applicable IEC and IEEE standards

Area of Usage
  • High Power Test Laboratories

  • Motor Starting

  • Electric Arc Furnaces

  • Induction Furnaces

Harmonic Filter Resistors

The widespread use of nonlinear loads such as power electronics based equipment and electric arc & ladle melt furnaces all around the world hinder the quality of electric power. One of the most important parameters for defining the power quality is harmonic distortion.

Features
  • Designed and tested to applicable IEC and IEEE standards

  • Stainless steel resistor elements

  • Excellent high voltage strength

  • Low inductance resistor elements for easy tuning

  • High thermal capacity

  • Pulsed power compatibility for filter energization and transformer inrush scenarios

  • Stainless steel, hot dip galvanized steel or aluminium enclosures on demand

  • Corrosion and heat resistant electrostatic paint for indoor and outdoor applications

  • Insulators with high creepage distance on demand for highly polluted areas and high altitudes

  • Compact design, dimensions can be adjusted according to customer's specific needs

  • Cooling fans on demand

  • Aluminium, hot dip galvanized steel or concrete support stands are available

  • Elevation stands are available

  • High temperature paint on demand

  • Bushing entry or cable entry

  • Bolted resistor element connections instead of welded connections, on demand

Anti-Condensation Space Panel Heaters

Anti-Condensation Space Heaters are designed to maintain the temperature of an electrical enclosure.

Anti-Condensation Heaters are used for elimination of water vapor contained inside the enclosures. They also provide frost protection by keeping the internal temperature of electrical enclosure above the freezing temperature. The Anti-Condensation Space (Panel) Heaters prevent condensation through convection.

Features

Operating Voltage: 110-240 V AC/DC (Other ratings on demand)

Rated Power: 50 W, 100 W (Other ratings on demand)

Heater Body: Extruded aluminium profile or stainless steel

  • High performance in polluted area

  • DIN Rail mount or flat surface mount

  • 35 mm DIN rail clip (HR.PTC,HRYr and HRu.Kr series)

  • Other voltage / power output options upon request

  • High reliability

  • Natural convection

  • Durable construction

Motor Starting & Control Resistors

Stator Connected Resistors

Motor Starting Resistors are used to reduce the voltage at the motor terminals and also decrease the starting current. Motor Starting Resistors are necessary because the self resistance of a motor armature is very low. When the voltage is first applied, excessive current will flow. For limiting this current, since there will be no resisting back electromotive force (emf),some series resistance can be added to the armature windings.

Rotor Connected Resistors

Rotor connected resistors are mainly used for the motor starting applications requiring high-starting torque like loaded belt conveyors in mining industry. By external resistors, it is possible to shift the motor maximum (break-down) torque up to starting torque point for motors under heavy loads during start-up. The resistors are splitted into some steps and controlled via contactors by motor starting control system. As the motor speed increases, the external rotor resistors are eliminated by shorting contactors until all external resistors are shorted out.

Area of Usage
  • Overhead cranes

  • Lift trucks

  • Machine tools

  • Conveyors

  • Cement plants

  • Industrial controls

  • Steel mills

  • Ships and submarines

  • On load starting motors

Dynamic Braking Resistors

Features
  • Manufactured for any power rating and duty cycle

  • Open type or enclosed construction

  • Custom designs are available in addition to standard modules

  • Suitable for any brand and model of Variable Frequency Drives (VFDs)

For high continuous powers and areas where space is a limitation, fan cooled braking resistors are also manufactured especially for marine, mining, and traction sectors.

Enclosure options:
  • Aluminium heat sink enclosed

  • Hot dip galvanized steel enclosed

  • Stainless steel enclosed

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