|Being first a manufacturer of power resistors, Post Glover has a vast
array of Dynamic Braking Resistors to choose from. This
allows us to offer the best possible technical and economic solution for
your particular application. We have worked with many OEMs and
built a broad knowledge of their product specifications for dynamic
brake resistors, so when you call in requesting a part, Post
Glover can cross-reference the part number and quote the needed part.
Post Glover is an original Rockwell Automation Encompass Partner and
will ship Rockwell Automation Dynamic Braking resistors up to 20 kW
same-day at no additional charge.
You can rely on
the industry's most innovative resistor manufacturer with over 100 years of industry
All we need is a part number to cross-reference
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How Post Glover Makes Your Life A Little Simpler
We make buying
resistors easy for our customers by striving to be the leader in cost and customer service.
We need just a few basic details to properly size your DBR:
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- Duty cycle
(time on/time off)
Ohms are determined by the drive manufacturer and are usually stated as
a range or minimum.
Watts are stated as
either a maximum braking power or continuous
braking power. In either case, the wattage rating of the resistor is
calculated by the braking cycle.
Braking cycle is
usually stated as a percentage; however, the actual
times on and off can be used to offer the optional resistor package
while minimizing size and cost.
An application requires a braking resistor rated 25 ohms with an
average power during braking of 2500 Watts. The duty cycle is 20% -
10 seconds on and 40 seconds off - with a cycle time of 50 seconds.
The ohmic value of the resistor is typically between -0% and +5% -
therefore, 25.0-26.25 ohms.
Dynamic Braking Resistor Elements
• Wirewound Resistor Element
- Ohms: 1.7 to
- Watts: up to
- Used primarily
for dynamic braking
• Edgewound Resistor Element
- Ohms: 0.5 to 300
- Watts: up to 400
- Used primarily for dynamic braking
- High ohmage handling in a smaller space
• Spiralwound Resistor Element
- Ohms: 0.05 to 9.0
- Watts: up to 1850
- Used for all applications
- High amperage handling in a smaller space
- Ohms: 1 to 34.9
- Watts: up to 1250
- Low cost Dynamic Braking element uses 50% less wire than Wirewound
- Fast cooling due to "paperclip" design
Standard features and options for all Post Glover Dynamic Braking
- Standard Nema 1 Enclosure Design
- Thermal overloads
- Two Point terminal block
- Factory Tested
- Convenient Conduit Knockouts
- Options: Powder Coated, Nema 3R, Stainless Steel
HOW DYNAMIC BRAKING RESISTORS WORK
State of the art
AC Variable Frequency Drives (VFD) are commonplace
today, creating the need for reliable, proven Dynamic Braking
Resistors that can be delivered quickly, completely assembled, and ready
for convenient installation at the job-site. Dynamic Braking
Resistors are used with AC VFD's to produce a braking torque in the motor
during overhauling conditions. The dynamic braking resistor is
connected across the DC bus and will see voltages as high as 800 volts.
The drive manufacturer normally determines the power rating
(watts) needed to prevent overheating during braking duty. The peak
braking current is determined by the specified resistance value. Each
drive manufacturer specifies a resistance range with a minimum to
prevent overcurrent and damage to the drive and a maximum value to give
adequate lower dissipation capability.
A three-phase variable frequency drive (VFD) consists of three
basic components - rectifier, DC line, and inverter - and a control
system to manage these three components as illustrated. The rectifier
converts the three-phase 60Hz AC input to a DC signal.
Depending on the system, an inductor, a capacitor, or
combination of these components smoothes the DC signal (reduces voltage ripple)
in the DC link part of the VFD. The inverter circuit converts the DC
signal into a variable frequency AC voltage to control the speed of the
During braking, the VFD ramps the frequency to zero. The
rotational energy of the motor and load are driven back through the
inverter to the DC bus.
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