Resistance Boxes

The Crane Control Equipments makes Resistance Boxes that are designed for both A.C. & D.C. applications. Our Stainless Steel Grid Resistance Boxes are used in winches,E.O.T Cranes, Rolling Mills, Steel Plants, Flour Mills, Cement Plants, Power Plants, Coil Mines etc., for speed controlling and developing of higher starting torque. We have carved a niche as one of the dominant Punched Steel Resistance Boxes Suppliers based in India.
These resistance Boxes can be designed to BSS/NEMA/IEEE standards.
We can also design and manufacture the resistors as per any specific standards specified by the customer.
Generally the resistor grids are either made of Stainless Steel wire or Punched Steel Sheet or in Fechral Material.
The Resistance boxes manufactured are suitable for a maximum temperature rise of 3750C as stipulated in BSS standards.
Stainless Steel Grid Resistance Boxes:-
In this case the resistor grids consist of corrosion resistant stainless steel wire or strips. Current rating generally ranges from 7 Amps to 80 amps continuous.
Higher ratings are possible by using multiple parallel paths.
The size of the wire is determined based on the technical data of the motor on which the Resistance Box is to be connected.
The drawn resistor material is uniform in section and free from any flaw or unevenness which is likely to cause local heating.
Suitable sizes of strips / wire are employed to give a wide range of current ratings.
The Grids are supported in such a way that the adjacent Grids cannot touch each other even under the most severe conditions of service.
The resistor elements consists of a continuous length of resistance wire or strip of uniform section formed into the required number of loops and bent so as to form frames with flanged edges similar to an element.
These are then mounted on Mica insulated Steel rods with Mica Washers between Steel spacers acting as Grid spacers.
The whole assembly thus forms a stack. Number of these stacks is formed to achieve the correct design of Resistance box required.
Punched Steel Resistors:-
In this case the Resistance boxes are made from Nickel Chromium Alloys Sheet Steel or Fechral as the case may be. Depending on the rating required the grids which are previously punched on a die fixture are assembled to from the desired Resistance Box.
The inherent strength of the steel itself is quite high and owing to the reinforced and pressed construction the rigidity of the Punched Grid is even higher.
Also since the grids are in form of Punched Sheet these are completely immune to shock and vibration.
They function reliably under the worst operating conditions.
These Resistors are available in a wide range from 19 amps to 234 amps continuous. Also the fixing dimensions and weight of various types of Grids are identical which means that different type of Grids required for various steps of Resistance would have identical size and mounting dimensions.
The heat dissipation of Punched Steel Grids is uniform irrespective of the current rating.
To enable us calculate the Resistance box we will be requiring the following information:
Capacity of MotorRotor Voltage of MotorRotor Amps of MotorNo. of Steps and type of Grids required