We offer high-performance and efficient range of DC Drives that is widely used for its compact designing and unmatched processing speed. Manufactured from high quality components, our DC Drives offer outstanding performance and durability.

DC SRC/ thyristor drives and motors remain common in industries, such as metals, cranes, mining and printing. The current trend is to replace DC systems with new AC drives and motors to reduce maintenance overheads, however, this can often be a significant task that requires the machinery to be taken out of service for an extended period while mechanical and electrical rework is undertaken. 

Utilizing the existing DC motor and upgrading the DC drive is often the most attractive option. DC motors are usually well built and capable of offering many more years of service, the project costs are usually much lower and the disruption and risks are minimized. Modern DC drives also provide many benefits,


A thyristor bridge is a technique commonly used to control the speed of a DC motor by varying the DC voltage. Examples of how a DC rectifier bridge operates are given on the next few pages. Voltage values given in these examples are used for explanation only. The actual values for a given load, speed, and motor vary.

It is important to note that the voltage applied to a DC motor be no greater than the rated nameplate. Armature windings are commonly wound for 500 VDC. The control logic in the drive must be adjusted to limit available DC voltage to 0 – 500 VDC. Likewise, the shunt field must be limited to the motor’s nameplate value.


A DC drives supplies voltage to the motor to operate at a desired speed. The motor draws current from this power source in proportion to the torque (load) applied to the motor shaft.

100% SPEED 0% LOAD

In this example an unloaded motor connected to a DC drive is being operated at 100% speed. The amount of armature current (Ia) and unloaded motor needs to operate is negligible. For the purpose of explanation a value of 0 amps is used.

The DC drive will supply only the voltage required to operate the motor at 100% speed. We have already learned the amount of voltage is controlled by the gating angle (COSα) of the thyristors. In this example 450 VDC is sufficient. The motor accelerates until CEMF reaches a value of Va – IaRa.

Remember that Va = IaRa + CEMF. In this example IaRa is 0, therefore CEMF will be approximately 450 VDC.

100% SPEED 100% LOAD

A fully loaded motor requires 100% of rated armature current at 100% speed. Current flowing through the armature circuit will cause a voltage drop across the armature resistance (Ra). Full voltage (500 VDC) must be applied to a fully loaded motor to operate at 100% speed. To accomplish this, thyristors are gated earlier in the sine wave (36.37°).

The DC drive will supply the voltage required to operate the motor at 100% speed. The motor accelerates until CEMF reaches a value of Va – IaRa.

Remember that Va = IaRa + CEMF. In this example armature current (Ia) is 100% and Ra will drop some amount of voltage. If we assume that current and resistance is such that Ra drops 50 VDC, CEMF will be 450 VDC.

ANON AUTOMATION make DC Drives are highly sophisticated and provided with adjustments as default factory set.

DC Drives has been specially designed for all industrial applications. Ambient temperature does not exceed 45 0 C  & it is not less than 10 0C .Ambient air is reasonable clean & dry and must be free of flammable or combustible vapors, steam  or corrosive gases.

Attitude should be 1000 meter above sea level maximum.


  • Semi-conductor fuses in the incoming lines for protection of thyristors.
  • di/dt protection
  • dv/dt protection
  • Surge suppressor across each thyristor
  • Electronic single phase protection
  • Electronic instantaneous over current trip
  • Over temperature protection for thyristor
  • Current sensing type field loss relay


Input supply                                              :           415volts +/-10%, 3 phase, 50 HZ.

Field voltage                                              :           220V DC

Thyristor bridge configuration              :           Full wave, fully controlled using six Thyristors.

Output voltage                                          :           440V DC infinite variable.

Speed regulation                                      :           +/- 1 % using tacho generator feedback +/- 3 % using Armature feedback.

Direction of rotation                               :           Bi-directional.

Static over-current trip (SOT)              :           150% peak of rated current.

Min. Voltage                                              :           Adjustable from up to 35% adjustable.

Max. Voltage                                             :           110% of rated voltage.

Acceleration/Deceleration time            :           From 2.0-30 sec.

Current limit                                              :           100% of full load rated current.

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