Resistance Boxes



Questionnaire For "ELEKTROMAG" Resistor

  SALIENT FEATURES

  • Well ventilated lowered enclosures on sides along the length, and load bearing members along the depth of adequate strength for free standing and top canopy for protection from rain.

  • Enclosure protection conforming to IP-00, IP11, IP-23, IP-33, and IP42 or totally enclosed IP-54 construction ore available as per customers requirements.

  • Resistor elements are made from unbreakable, rustless:

    • Stainless Wire formed Grid (AISI 304) typr 'SS'

    • Stainless Steel Wire (AISI 304) wound on Steel Plate with porcelain channal on edges type'WW'

    • Punched Stainless Steel Plate type Grid(AISI 304) type 'PS'.

    • Punched Stainless Steel Plate type Grid(AISI 406-Fechral) type 'FS'.

  • All terminal are located at the bottom and are clearly marked with printed name plates to facilitate easy identification and wiring. Each junction point is well insulated from the other by means of mica tubes and micawahers.

  • The Resistors are designed to meet both indian as well as International Standards such as IS:1822-1967, IEEE-32. BS:587 and VDE.


STAINLESS STEEL WIRE FORMED GRID RESISTANCE BOX TYPE : 'SS'

Resistors type 'SS' are manufantured from Stainless Steel (AISI 304) having temperature co-efficient of 0.094% per degC, wire formed grids, making them rustless, unbreakable and light in weight. therre is provision at each grid to have a tapping, so that resistance value between steps could be altered. These Grids are generally used for Rotor Current of maximum 54 Amps for 10 minutes and 42 Amps for continuous duty. As for Rotor Currents that are higher than these values, two or three grids will have to be used in parallel, thus making the Resistor Assembly costlier. These Resistors are designed and manufactured to meet different classes of service in various industries such as Screw Feeders, Conveyors, Elvators, Coke Oven Machines, E.O.T. Cranes, Flour Mills, Rope Haulages, Winches, Rubber Mixing Mills, etc. for developing starting torque or for speed control.


WIRE WOUND RESISTANCE BOX TYPE : 'WW'

Resistors type 'WW' are manufactured with Stainless Steel Wire(AISI 304) having temperature co-efficient of 0.094% per deg.C wound on Steel Plate with Porcelain Channels at the edges. These Resistortsare widely used for Higher Resistance values, but, lower Current, e.g. as Economy Resistors have provision for termination on any plate.


PUNCHED STAINLESS STEEL GRID RESISTANCE BOX TYPE:'PS'

Resistors type 'PS'are manufactured with grids punced out from Stainless Steel Plate (AISI 304). Each Resistor Grid has provision for termination which helps in changing the step Resistance Value of a given Resistor Assembly without dismantling the whole assembly. These grid retain the end of the Grids and steel remain cool which eleminates hot spots from developing. These Resistors are idealy suitable for higher currents are being patronised for heavy duty service for use in Steel Mills, Coal Mines, Foundries, Forklift Trucks, Dynamic Breaking resistors, etc and those applications where the electrical equipment may be subjected to severe vibrations.


PUNCHED FECHRAL GRID RESISTANCE BOX
TYPE : 'FS'

Resistors type 'FS' are manufactured with grids punched out form Plates of Steel - Chromium - Aluminium alloy (widely known as 'Fe Cr or AISI 406).


GENERAL CONSTRUCTION FEATURES FOR ALL RESISTORS

All the Resistors are assembled on elctro plate heavy guage Steel Trays at both ends and bolted loured coverrs at the sides to permit passage of air and a canopy at the top to prevent dirt and water from entring the Assembly. The whole assembly is drip proof, IP-23, natural air cooled. Resistors in open execution having IP-00 protection for mounting inside the cubical of customers can also be supplied. Enclosure protection of IP-33, IP-42 and IP-54 can also be supplied on request at extra cost. The Grids are supported on electro plated steel rods insulated with export qulity Mica Tubes. Insulation between grids to grids is by means of Mica Washers. Electrical path between two grids are achieved by means of electro plated steel washers.


TEMPERATURE RISE LIMIT

Unless, otherwise specifically conformed by us, all the resistors, except Dynamic Breaking Resistors are designed for Tempreture Rise upto 375 deg. C. Other Temprature Rise limits can be designed as per customers specifications such as 275, 250, 225, 220 deg. C and for that matter any limit that the customer specifies. Dynamic Breaking Resistors are designed for maximum Temperature Rise of 760 deg. C as per IEEE 32.


MANUFACTURER'S TOLERANCE

The total Resistance values and the Step Resistance Values measured actually will be manufacturers tolarance of +/- 10%.


TESTS CONDUCTED AT OUR WORKS

Only the following tests are conducted by us or jointly with the customers reprenstative at our Works before despatch:

  • Visual inspection for general workmanship, quality and dimension and finish.
  • Resistance values measutements for total resistance per phase and step resistance values with Electronic digital Ohm meter.

  • Measurement of Insulation Resistance (Megger) by Insulation Tester.

  • High Voltage Test (Flash Test) - 2 KV for 1 Minute between live resistor and eather members.


CAST IRON RESISTORS TYPE : 'CI'

Cast iron Grid type Resistor has now become obselete and is no more by Crane manufacturers and Steel Plants abroad and in the country due to various disadvantages. We are detaling below some of the major disadvantages of Cast iron Grids and advantages of Stainless Steel Grids :

STAINLESS STEEL GRIDS CAST IRON GRIDS
Advantages Disadvantages
S.S. Grids do not break and can withstand any amount of vibrations. Due to low impact strenth, Grids are likely to break when subjected to vibrations normally encountered on EOT Cranes.
S.S. Grids are free from rust and can be installed in moist and saline atmosphere. C.I. Grids rust specially when installed in moist and saline atmosphere.
S.S. Grids are suitable for all types are duty conditions. C.I. Grids are normally used for only Starting and Intermittent duty.
S.S. Grids take less time for cooling because of the higher ratio of surface to mass. C.I. Grids take longer time to cool because of the low ratio of surface to mass.


DATA REQUIRED FROM CUSTOMER FOR OFFERING RESISTOR ASSEMBLY

The following basic data is required for furnishing an offer and subsequently supply the unit if the order is placed on us:

  • HP/KW of the Motor.

  • Rotor Voltage of the Motor (RV)

  • Rotor Current of the Motor (RA)

  • Duty cycle of the Motor (25%, 40%, 60% OR 100% CDF)

  • Type of Controller (Master Controller or Push Button or Drum Controller) and its No. of Steps used by you to cut the resistance.

  • Type of Resistor Grid Element required (SS, WW, PS or FS)

  • Type of Encloser Protection required - IP-23, IP-33, IP-42 or IP-54)


NEUTRAL GROUNDING RESISTOR

An Earthing Resistor is primarily a safety device. It drastically reduces shoke hazards to personnel and equipment. We have, therefore, developed Earthing Resistors for your benefit. Our Earthing Resistors have been tested by the Indian Institute of Technology, Powai, for High Voltage and withstood the test successfully. They provide effective protection against high voltage.

The Resistors are suitably insulated to withstand working pressures upto 23 K.V./33 K.V. The Grids are manufactured from a special alloy of stainless steel which makes them rustless and unbreakable thus eliminating maintenance problem and suitable for installation in outdoor atmosphere.

For any further guidance, please contact Elektromag.

Note : The design and dimensions are subject to alterations without prior notice due to constant development for better performance.

E.O.T Crane Control Gear Equipment