when the motor is braked, it is desired that it comes to a halt in minimum possible time. Hence the ohmic value of DBR is selected such that it causes maximum braking current at the instant of starting the braking.This current depends on the overload capacity of the motor. The Ohmic value of DBR isR= Vr/IP where Vr is the motor armature rated voltage andIp is permissible current. Dynamic braking starts with maximum current and falls exponentially with time,while the field current is maintained constant.The armature voltage and motor speed also decay exponentially.The motor comes to a halt in a time period equal to apprx.twice the time constant(r) as friction also aids the braking process.In most applications r is less than 5 secs and hence dynamic braking is less than 10 secs.
King Industrie Dynamic Braking Resistors are consist of smooth wound, wire wound or edge wound type resistor coils mounted in ventilated enclosures. Our resistors can be used in any type AC or DC power circuit/application. They are designed for many types of applications: continuous duty applications where high resistance and low current are required, continuous duty applications where low resistance and high current are required and low current applications. Dynamic breaking Braking resistors are also available with a special stainless steel enclosure with Degree of Enclosure protection up to IP42
DYNAMIC BREAKING RESISTORS is the simplest and most widely used method of braking a load driven through a d.c.motor as it involves no wear & tear unlike mechanical brakes. For dynamic braking, the motor armature is closed on a suitably designed Dynamic Braking Resistor(DBR),while the motor field remains energised.The kinetic energy stored in motor and load gets dissipated in the DBR and the system comes to a halt within a few seconds.
