• Mill galvanized enclosure
• Nema 1
• Temperature switch
• Edgewound or
  Wirewound Elements

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 are an original Encompass partner to
Rockwell Automation and have built a broad knowledge of their product
specifications for dynamic braking resistors, so when you call in
requesting a part, Post Glover can quote the needed part fast. Post
Glover 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
experience.

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. The Rockwell Automation Proposal
works links use the following steps to specify the correct dynamic
braking resistor for your application.

Just a few basic details are needed to properly size your DBR:

• Ohms

• Watts

• Duty cycle (time on/time off)
  Ohms are determined by the drive 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.

Example
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 Element Types

• Smoothwound Resistor Element

• Ohms: 1.7 to 1500

• Watts: up to 1100

• Used primarily for dynamic braking

• Adjustable rating resistor

• Wirewound Resistor Element

• Ohms: 0.5 to 300

• Watts: up to 400

• Used primarily for dynamic braking

• High ohmage handling in a smaller space
   

• Edgewound Resistor Element

• Ohms: 0.05 to 9.0

• Watts: up to 1850

• Used for all applications

• High amperage handling in a smaller space
   

• Spiralwound Resistor Element

• Ohms: 1 to 34.9

• Watts: up to 1250

• Low cost Dynamic Braking element uses 50% less wire than Wirewound design

• Fast cooling due to "paperclip" design
  

• Flat Pack Resistor Element

• Ohms: 0.75 to 10

• Watts: up to 500

• Aluminum case resistor used primarily for light-duty braking of variable frequency drives

• Completely sealed resistor for use in "wash down" environments

Only With Post Glover Do You Get All These Features and Options.

• 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 Rockwell Automation drive 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 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 induction motor.

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.

More Information
ROCKWELL JOURNAL - UNDERSTAND HIGH RESISTANCE GROUND FAULT PROTECTION
DYNAMIC BRAKING ENCLOSURE DIMENSIONS DB103-07