Resistors save space for dynamic braking

A new standard range of enhanced planar pulse resistors for dynamic braking provide high-performance solutions for variable speed AC motor drives and other pulse absorbing applications.

A new standard range of enhanced planar pulse resistors for dynamic braking provide high-performance solutions for variable speed AC motor drives and other pulse absorbing applications, focusing on an integrated solution to reduce space within a complete unit.

John Graham, Marketing and Sales Director said: "The braking resistor (WDBR Series) is used to limit the voltage rise, which would occur during a motor speed reduction phase.

Here the motor supplies electrical power back to the source power electronics, thus causing the DC voltage supply to increase.

The intervention of the WDBR prohibits extensive damage to the inverter electronics".

In most cases the WDBR outperforms the equivalent wire-wound resistor in terms of pulse handling capability.

As a technology using series parallel combination the thick film on steel planar power resistor is suitable for motor drive applications beyond 10kW.

The individual resistor offers a built in failsafe overload mechanism, and is available with push on tags or flying leads.

Designers will find that many of the issues associated with traditional style braking resistors are resolved with use of the WDBR Series part.

The high reliability planar construction, allows integral attachment to the motor drive, making this a compact component with given functionality.

As attachment takes the form of a single bolt arrangement, the resistor also offers reduced installation costs.

It offers two power ratings of 2 and 5kW and standard ohmic values of 25R, 50R, 100R and 150R with a tolerance of +/-10%.

Continuous power ratings are up to 300W, and minimum dielectric withstand voltage is 2500V.

Typical inductance is less than 5uH and hot spot temperature is 365C.

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