Control Techniques DB Resistors Catalog Page

Power Accessories

for

AC and DC Drives

DYNAMIC BRAKING RESISTORS

The DC bus voltage level of a drive increases while
the motor is re-generating, i.e. ramping to a stop.
Dynamic braking resistors provide a means of rapidly
stopping a rotating motor and load while maintaining
an acceptable bus voltage level. The mechanical energy
stored in the spinning mass is converted into electrical
energy and quickly dissipated as heat through a resistor.
Control Techniques offers resistor kits available for both
AC and DC drives.

Dynamic Braking for DC Drives

DC drives provide an exponential stopping profile when
a dynamic brake resistor is applied across the motor’s
armature circuit (when the motor acts as a DC
generator). This type of braking can occur only when the
drive is configured for coast stop and power has been
removed from the motor (stop commanded). To apply a
dynamic brake resistor to a DC drive, a motor contactor
with a DB pole is required. This motor contactor is
standard on Quantum III DC drives up through 250 hp.

OVERLOAD PROTECTION

Dynamic Braking for AC Drives

AC drives provide a constant torque stopping profile
when a dynamic brake resistor is applied across the DC
bus circuit. Dynamic braking can be employed under a
stop command or anytime a decrease in motor speed
is commanded, provided the AC drive is enabled and
programmed for ramp stop (fast ramp mode).

Regen to line is also a preferred way to handle dynamic
braking and is an option on Focus 3, Mentor II and
Quantum III DC drives.

The brake is active anytime the system is enabled.
Therefore, the braking circuit must be protected with an
overload device.

The Commander SK, GP20 and Unidrive SP drives
are equipped standard with built-in dynamic braking
transistors. Simply select the proper braking resistor
needed for the size of drive and duty cycle.

Control Techniques offers two types of dynamic braking
kits for AC Drives. The E-stop duty kits provide a means
of quickly stopping a motor / load as well as providing
the ability to dissipate energy created by either a change
in motor speed or a line transient.

The cyclic duty kits are intended for more severe
applications that need the capability to dissipate
regenerated energy on a more continuous or repetitive
basis such as indexers, feeders and dynamometers.

Power

Accessories

383

DB Resistors for AC Drives

E-STOP DUTY

Panel mounted DB resistors are designed for non-cyclic
use where energy dissipation from an active drive is
required. Resistors are supplied with mounting hardware
unless otherwise noted.

These kits are designed to meet or exceed NEMA
standard 7-15-1970, which states “DB resistors will not
exceed their rated temperature rise when the drive is
braked from maximum speed to standstill three times
in rapid succession with a load inertia equal to or less
than the motor inertia”. They are designed to provide
150% braking torque (peak at max speed for DC drives,
constant for AC drives) for 1800 rpm base speed motors.

Note: The Commander GP20 and Unidrive SP Size 1
and 2 can be equipped with a zero-space, heatsink
mountable DB resistors.

INTERNAL DYNAMIC BRAKING RESISTORS

Commander SK (size 2), GP20 and Unidrive SP

Frame Size DC Resistance Power Rating Order Code

1

75 W

50W SM-Heatsink-DBR1

CYCLIC DUTY

NEMA 1 DB resistor kits include a wall mount enclosure
with built-in junction box, a terminal strip,
a normally closed thermal contact (klixon switch) and
resistors pre-wired with high-temperature Teflon wire.

These heavy-duty kits have been designed to provide
dynamic braking for cyclic and continuous braking
applications. There are three levels available: 10%, 25%
and 33%. These levels refer to the continuous allowable
braking level (ie. 25% equals 25% of rated motor
braking torque) or the maximum allowable duty cycle
rates with maximum specified “on-time” limitations
(refer to illustration below).

Duty Cycle

E-STOP DUTY CASE DB RESISTORS FOR COMMANDER SK, GP20 & UNIDRIVE SP SERIES AC DRIVES

Control Techniques E-Stop duty case dynamic braking
resistors provide the energy dissipation required for a
drive system while keeping the installation as compact
as possible. See drive heatsink options in the drive
section of the catalog.

Accessories

Power

2

DRIVE ORDER CODE LEGEND
y= SK for Commander SK, or CGP for Commander GP20,

or SP for Unidrive SP
z= CGP for Commander GP20, or SP for Unidrive SP

37.5 W

100W SM-Heatsink-DBR2

230VAC

Drive Order Code

SKA1200025 8200-00450 9 x 1.5 x 0.75

SKA1200037 8200-00451 6 x 3 x 1.5

SKA1200055 8200-00452 6 x 3 x 1.5

z1201 & SKA1200075 8200-00453 6 x 3 x 1.5

z1202 & SKBD200110 8200-00454 6 x 3 x 1.5

z1203 & SKBD200150 8200-00455 6 x 3 x 1.5

z1204 & SKCD200220 8200-00456 9 x 3 x 1.5

460VAC

Drive Order Code

SKB3400037 8200-00412 6 x 3 x 1.5

SKB3400055 8200-00413 7.5 x 3 x 1.5

z1401 & SKB3400075 8200-00414 7.5 x 3 x 1.5

SKB3400110 8200-00415 9 x 3 x 1.5

z1402 & SKB3400150 8200-00416 9 x 3 x 1.5

z1403 & SKC3400220 8200-00417 12 x 3 x 1.5

z1404 & SKC3400300 8200-00418 12 x 3 x 1.5

z1405 & SKD3200400

Case Resistor

Order Number

Case Resistor

Order Number

8200-00419 12 x 3 x 1.5

Dimensions (in.)

L x D x H

Dimensions (in.)

L x D x H

384