Braking Resistors

Variable speed drives
Altivar Process
Option: Braking resistors

Braking resistors allow Altivar Process drives to operate while braking to a standstill, by dissipating the braking energy. They enable maximum transient braking torque.

Braking resistors are designed to be located outside the enclosure, but should not inhibit natural cooling. Air inlets and outlets must not be obstructed in any way. The air must be free of dust, corrosive gas, and condensation.

Several resistor models are available, depending on the drive rating:

• With IP20 and IP23 casing and thermal monitoring provided by temperaturecontrolled switch or by the drive
• The internal circuits of Altivar Process drives rated 220 kW/350 HP or less at 400...480 V and 45 kW/60 HP or less at 200...240V have a built-in dynamic brake transistor.
• An external braking unit is necessary for wall-mounting Altivar Process drives above 220 kW at 400...480 V as well as 55 kW/75 HP and 75 kW/100 HP at 200...240 V

Braking resistors are designed for a defined cycle (see the three cycle types defined below). Depending on your applications and cycles, you can use these resistors or define a new value:

• Braking resistors for light braking cycles for machines with cycles and inertia. The braking power is limited to 1.5 Tn for 0.8 s every 40 s.
• Braking resistors for medium braking cycles for machines with high inertia and conveyors. The braking power is limited to 1.35 Tn for 4 s every 40 s.
• Braking resistors for severe braking cycles for machines with very high inertia and vertical movements (hoisting). The braking power is limited to 1.65 Tn for 6 s and Tn for 54 s every 120 s.