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Appendix
A
Dynamic Brake Selection Guide
The Dynamic Braking Selection Guide provided on the following pages contains detailed information on selecting and using dynamic brakes.
Dynamic Braking
www.abpowerflex.com
Selection Guide
A-2
Dynamic Brake Selection Guide
Important User Information
Solid state equipment has operational characteristics differing from those of electromechanical equipment. “Safety Guidelines for the Application, Installation
and Maintenance of Solid State Controls” (Publication SGI-1.1 available from your local Allen-Bradley Sales Office or online at http://www.ab.com/manuals/gi) describes some important differences between solid state equipment and hard-wired electromechanical devices. Because of this difference, and also because of the wide variety of uses for solid state equipment, all persons responsible for applying this equipment must satisfy themselves that each intended application of this equipment is acceptable.
In no event will the Allen-Bradley Company be responsible or liable for indirect or consequential damages resulting from the use or application of this equipment.
The examples and diagrams in this manual are included solely for illustrative purposes. Because of the many variables and requirements associated with any particular installation, the Allen-Bradley Company cannot assume responsibility or liability for actual use based on the examples and diagrams.
No patent liability is assumed by Allen-Bradley Company with respect to use of information, circuits, equipment, or software described in this manual.
Reproduction of the contents of this manual, in whole or in part, without written permission of the Allen-Bradley Company is prohibited.
Throughout this manual we use notes to make you aware of safety considerations.
!
ATTENTION: Identifies information about practices or circumstances that can lead to personal injury or death, property damage, or economic loss.
Attentions help you:
• identify a hazard
• avoid the hazard
• recognize the consequences
Important: Identifies information that is especially important for successful application and understanding of the product.
Shock Hazard labels may be located on or inside the drive to alert people that dangerous voltage may be present.
Burn Hazard labels may be located on or inside the drive to alert people that surfaces may be at dangerous temperatures.
Table of Contents
What This Guide Contains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
How Dynamic Braking Works . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Dynamic Brake Components . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
How to Determine Dynamic Brake Requirements . . . . . . . . . . . 2-1
Determine Values of Equation Variables . . . . . . . . . . . . . . . . . . 2-4
Example Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9
Evaluating the Capability of the Internal Dynamic Brake Resistor . .
How to Select an External Dynamic Brake Resistor . . . . . . . . . 4-1
ii
Notes:
Table of Contents
Section
1
What This Guide Contains
This Selection Guide contains the information necessary to determine whether or not dynamic braking is required for your drive application and select the correct resistor rating.
•
Section 1 provides an overview of dynamic braking principles.
•
Section 2 steps you through the calculations used to determine if dynamic braking is required for your drive application.
•
Section 3 steps you through the calculations used to determine if the internal dynamic brake option is adequate for your drive application.
•
Section 4 steps you through the calculations needed to select an externally mounted dynamic brake resistor for your drive application.
How Dynamic Braking Works
When an induction motor’s rotor is turning slower than the synchronous speed set by the drive’s output power, the motor is transforming electrical energy obtained from the drive into mechanical energy available at the drive shaft of the motor. This process is referred to as
motoring. When the rotor is turning faster than the synchronous speed set by the drive’s output power, the motor is transforming mechanical energy available at the drive shaft of the motor into electrical energy that can be transferred back to the drive. This process is referred to as
regeneration.
Most AC PWM drives convert AC power from the fixed frequency utility grid into DC power by means of a diode rectifier bridge or controlled
SCR bridge before it is inverted into variable frequency AC power.
Diode and SCR bridges are cost effective, but can only handle power in the motoring direction. Therefore, if the motor is regenerating, the bridge cannot conduct the necessary negative DC current, the DC bus voltage will increase and cause an overvoltage fault at the drive. More complex bridge configurations use SCRs or transistors that can transform DC regenerative electrical power into fixed frequency utility electrical energy. This process is known as line regeneration.
A more cost effective solution can be provided by allowing the drive to feed the regenerated electrical power to a resistor which transforms it into thermal energy. This process is referred to as dynamic braking.
1-2
Dynamic Brake Components
A Dynamic Brake consists of a Chopper (the chopper transistor and related control components are built into PowerFlex drives) and a
Dynamic Brake Resistor.
shows a simplified Dynamic Braking schematic.
Figure 1.1 Simplified Dynamic Brake Schematic
+ DC Bus
Dynamic
Brake
Resistor
FWD
Voltage
Divider
To
Voltage
Control
Signal
Common
To
Voltage Dividers
Chopper
Transistor
Chopper Transistor
Voltage Control
FWD
Voltage
Divider
To
Voltage
Control
– DC Bus
Chopper
The Chopper is the Dynamic Braking circuitry that senses rising DC bus voltage and shunts the excess energy to the Dynamic Brake Resistor. A
Chopper contains three significant power components:
The Chopper Transistor is an Isolated Gate Bipolar Transistor (IGBT).
The Chopper Transistor is either ON or OFF, connecting the Dynamic
Brake Resistor to the DC bus and dissipating power, or isolating the resistor from the DC bus. The most important rating is the collector current rating of the Chopper Transistor that helps to determine the minimum resistance value used for the Dynamic Brake Resistor.
1-3
Chopper Transistor Voltage Control regulates the voltage of the DC bus during regeneration. The average values of DC bus voltages are:
•
375V DC (for 240V AC input)
•
750V DC (for 480V AC input)
Voltage dividers reduce the DC bus voltage to a value that is usable in signal circuit isolation and control. The DC bus feedback voltage from the voltage dividers is compared to a reference voltage to actuate the
Chopper Transistor.
The Freewheel Diode (FWD), in parallel with the Dynamic Brake
Resistor, allows any magnetic energy stored in the parasitic inductance of that circuit to be safely dissipated during turn off of the Chopper
Transistor.
Resistor
The Resistor dissipates the regenerated energy in the form of heat. The
PowerFlex Family of Drives can use either the internal dynamic brake resistor option or an externally mounted dynamic brake resistor wired to the drive.
The internal resistor kit for the drive may be used for the application if the required energy, deceleration time, and duty, all are small enough to be within the capabilities of the resistor.
The internal resistor is protected by drive software so that its duty cycle capability is not exceeded. The duty cycle is attenuated by the magnitude of the ‘DB Suppress’ signal coming from the Thermal Model algorithm.
The Thermal Model algorithm uses resistor thermal property constants to compute DB resistor temperature from applied resistor power that is computed from knowing the DB transistor duty cycle (DutyDB ). When the Thermal Model computes that the DB resistor temperature is nearing the maximum rise allowed, the ‘DB Suppress’ signal begins to rise reaching full value when maximum temperature rise is reached..
When the internal resistor cannot provide the required braking capability an external resistor may be supplied by the user that has more capability
A DB Resistance Auto-Detect algorithm is used. This algorithm is executed as part of the ‘power-up’ diagnostics and is only re-enabled until the drive is fully powered down again. This algorithm checks that the resistance measured across the DB terminals of the power board is within limits that are stored in the power board EEPROM.
1-4
The algorithm runs as follows:
•
Opens the precharge relay if not already open.
•
Pulses the DB transistor on in a series of increasing width pulses.
•
Measures the resulting capacitor bank voltage drop during each pulse.
•
Verifies the drop is within allowed limits (stored in the power board
EEPROM).
If the resistance measured is out of limits and the DB regulator is enabled then the ‘DB Resistance Out of Range’ fault is set. If the DB
Regulator is not enabled with this out of limits condition, no fault is set.
But, if some time after power-up the [Bus Reg Mode] parameter is set to enable the DB Regulator, the fault is set at that time.
Section
2
How to Determine Dynamic Brake Requirements
When a drive is consistently operating in the regenerative mode of operation, serious consideration should be given to equipment that will transform the electrical energy back to the fixed frequency utility grid.
As a general rule, Dynamic Braking can be used when the need to dissipate regenerative energy is on an occasional or periodic basis. In general, the motor power rating, speed, torque, and details regarding the regenerative mode of operation will be needed in order to estimate what
Dynamic Brake Resistor value is needed.
The Peak Regenerative Power of the drive must be calculated in order to determine the maximum resistance value of the Dynamic Brake
Resistor. Once the maximum resistance value of the Dynamic Brake
Resistor current rating is known, the required rating and number of
Dynamic Brake Resistors can be determined. If a Dynamic Brake
Resistance value greater than the minimum imposed by the choice of the peak regenerative power is made and applied, the drive can trip off due to transient DC bus overvoltage problems. Once the approximate resistance value of the Dynamic Brake Resistor is determined, the necessary power rating of the Dynamic Brake Resistor can be calculated.
The power rating of the Dynamic Brake Resistor is estimated by applying what is known about the drive’s motoring and regenerating modes of operation. The Average Power Dissipation must be estimated and the power rating of the Dynamic Brake Resistor chosen to be greater than that average. If the Dynamic Brake Resistor has a large thermodynamic heat capacity, then the resistor element will be able to absorb a large amount of energy without the temperature of the resistor element exceeding the operational temperature rating. Thermal time constants in the order of 50 seconds and higher satisfy the criteria of large heat capacities for these applications. If a resistor has a small heat capacity (defined as thermal time constants less than 5 seconds) the temperature of the resistor element could exceed its maximum.
Peak Regenerative Power can be calculated as:
•
Horsepower (English units)
•
Watts (The International System of Units, SI)
•
Per Unit System (pu) which is relative to a value
The final number must be in watts of power to estimate the resistance value of the Dynamic Brake Resistor. The following calculations are demonstrated in SI units.
2-2
Gather the Following Information
•
Power rating from motor nameplate in watts, kilowatts, or horsepower
•
Speed rating from motor nameplate in rpm or rps (radians per second)
•
Motor inertia and load inertia in kg-m
2
or lb.-ft.
2
•
Gear ratio (GR) if a gear is present between the motor and load
•
Motor shaft speed, torque, and power profile of the drive application
shows the speed, torque, and power profiles of the drive as a function of time for a particular cyclic application that is periodic over t
4 seconds. The desired time to decelerate is known or calculable and is within the drive performance limits. In
variables are defined:
ω
(t)
= Motor shaft speed in radians per second (rps)
ω
=
2
π
N
----------
60
N(t)
= Motor shaft speed in Revolutions Per Minute (RPM)
T(t)
= Motor shaft torque in Newton-meters
1.0 lb.-ft. = 1.355818 N-m
P(t) = Motor shaft power in watts
1.0 HP = 746 watts
ω
ω
-P b o b
= Rated angular rotational speed
Rad
--------s
= Angular rotational speed less than
ω b
(can equal 0)
Rad
--------s
= Motor shaft peak regenerative power in watts
2-3
Figure 2.1 Application Speed, Torque and Power Profiles
ω
ω
(t) b
ω o
0 t1 t2 t3 t4 t1 + t4
T(t)
0
P(t) t1 t2 t3 t4 t1 + t4
-Pb
0 t1 t2 t3 t4 t1 + t4 t t t
2-4
Determine Values of Equation Variables
Step 2 Total Inertia
J
T
=
J m
+
(
GR
2
×
J
L
)
J
T
J m
= Total inertia reflected to the motor shaft (kg-m
= Motor inertia (kg-m
2
or lb.-ft.
2
)
2
GR = Gear ratio for any gear between motor and load
(dimensionless)
J
L
= Load inertia (kg-m
2
or lb.-ft.
2
)
1.0 lb.-ft.
2
= 0.04214011 kg-m
2
or lb.-ft.
2
)
Calculate Total Inertia:
J
T
=
[ oooooooooo
]
+
( oooooooooo
× oooooooooo
)
Record Total Inertia:
J
T
=
2-5
Step 3 Peak Braking Power
P b
=
J
T
[ ω
( b
( t
3
ω
– t
–
2
)
ω ) ]
----------------------------------------
P b
= Peak braking power (watts)
1.0 HP = 746 watts
J
ω
ω
T b o
= Total inertia reflected to the motor shaft (kg-m
2
)
= Rated angular rotational speed
Rad
--------s
=
2
π
N
------------
60 b
= Angular rotational speed, less than rated speed down to zero
Rad
--------s
= Rated motor speed (RPM) N b t
3
– t
2
= Deceleration time from
ω b
to
ω o
(seconds)
Calculate Peak Braking Power:
P b
=
[ ooooooooo
] × [
( ooooooooo ooooooooo
]
–
× ( ooooooooo ooooooooo
)
– ooooooooo
)
Record Peak Braking Power:
P b
=
Compare the peak braking power to that of the rated motor power. If the peak braking power is greater that 1.5 times that of the motor, then the deceleration time (t
3 go into current limit.
– t
2
) needs to be increased so that the drive does not
2-6
Step 4 Minimum Power Requirements for the Dynamic Brake
Resistors
It is assumed that the application exhibits a periodic function of acceleration and deceleration. If (t
3
– t
2
) equals the time in seconds necessary for deceleration from rated speed to
ω o
speed, and t
4
is the time in seconds before the process repeats itself, then the average duty cycle is (t
3
– t
2
)/t
4
. The power as a function of time is a linearly decreasing function from a value equal to the peak regenerative power to some lesser value after (t
3
– t
2
) seconds have elapsed. The average power regenerated over the interval of (t
3
– t
2
) seconds is:
P
-----
2
×
( ω b
+
ω b
ω )
P b
ω b
ω o
P av
= Average dynamic brake resister dissipation (watts) t
3
– t
2
= Deceleration time from
ω b
to
ω o
(seconds) t
4
= Total cycle time or period of process (seconds)
= Peak braking power (watts)
= Rated angular rotational speed
= Angular rotational speed,
Rad
--------s less than rated speed down to zero
Rad
--------s
The Average Power in watts regenerated over the period t
4
is:
P av
=
( t
2
)
-----------------t
–
4 t P
-----
2
( ω b
+
ω b
ω
------------------------
)
Calculate Average Power in watts regenerated over the period t
4
:
P av
=
( oooooo
– oooooo
[ oooooo
]
)
×
[ oooooo
]
2
×
( oooooo
[
+ oooooo oooooo
]
)
Record Average Power in watts regenerated over the period t
4
:
P av
=
2-7
Step 5 Percent Average Load of the Internal Dynamic Brake
Resistor
Skip this calculation if an external dynamic brake resistor will be used.
AL
=
P
-------100
P db
×
AL = Average load in percent of dynamic brake resistor
P av
= Average dynamic brake resistor dissipation calculated in
P db
= Steady state power dissipation capacity of dynamic brake resistors obtained from
(watts)
Calculate Percent Average Load of the dynamic brake resistor:
AL
=
[
[ oooooooooo
----------------------------------oooooooooo
]
]
×
100
Record Percent Average Load of the dynamic brake resistor:
AL =
The calculation of AL is the Dynamic Brake Resistor load expressed as a percent. P db is the sum of the Dynamic Brake dissipation capacity and is obtained from
. This will give a data point for a line to be
drawn on one the curves provided in
Table 2.A Rated Continuous Power for Internal DB Kits
Drive Voltage Frame
P db
Internal Resistor Continuous Power (watts)
230
230
230
230
A
B
C
D
48
28
40
36
460
460
460
460 (15HP)
460 (20HP)
C
D
A
B
D
48
28
40
36
36
2-8
Step 6 Percent Peak Load of the Internal Dynamic Brake Resistor
Skip this calculation if an external dynamic brake resistor will be used.
PL
=
P
-------100
P db
×
PL = Peak load in percent of dynamic brake resistor
P av
P db
= Peak braking power calculated in Step 2 (watts)
= Steady state power dissipation capacity of dynamic brake resistors obtained from
(watts)
Calculate Percent Peak Load of the dynamic brake resistor:
PL =
[
[ oooooooooo
----------------------------------oooooooooo
]
]
×
100
Record Percent Average Load of the dynamic brake resistor:
PL
=
The calculation of PL in percent gives the percentage of the instantaneous power dissipated by the Dynamic Brake Resistors relative to the steady state power dissipation capacity of the resistors. This will give a data point to be drawn on one of the curves provided in
2-9
Example Calculation
A 10 HP, 4 Pole, 480 Volt motor and drive is accelerating and decelerating as depicted in
.
•
Cycle period t
4
is 40 seconds
•
Rated speed is 1785 RPM and is to be decelerated to 0 speed in 15.0
seconds
•
Motor load can be considered purely as inertia, and all power expended or absorbed by the motor is absorbed by the motor and load inertia
•
Load inertia is 4.0 lb.-ft.
2
and is directly coupled to the motor
•
Motor rotor inertia is 2.2 lb.-ft.
2
Calculate the necessary values to choose an acceptable Dynamic Brake.
Rated Power
=
10 HP
×
746 watts
=
7.46 kW
This information was given and must be known before the calculation process begins. This can be given in HP, but must be converted to watts before it can be used in the equations.
Rated Speed
=
ω b
=
1785 RPM
=
2
π ×
1785
----------
60
=
186.98 Rad
------------------------s
Lower Speed =
ω o
= 0 RPM = 2
π ×
0
-----
60
=
0 Rad
------------s
This information was given and must be known before the calculation process begins. This can be given in RPM, but must be converted to radians per second before it can be used in the equations.
Total Inertia = J
T
= 6.2
lb.-ft.
2
= 0.261 kg-m
2
This value can be in lb.-ft.
2
or Wk
2
, but must be converted into kg-m
2 before it can be used in the equations.
Deceleration Time
=
( t
3
– t
2
)
=
15 seconds
Period of Cycle = t
4
= 40 seconds
2-10
V d
= 750 Volts
This was known because the drive is rated at 480 Volts rms. If the drive were rated 230 Volts rms, then V d
= 375 Volts.
All of the preceding data and calculations were made from knowledge of the application under consideration. The total inertia was given and did not need further calculations as outlined in
Peak Braking Power
=
P b
=
J
T
[ ω
( b
( t
3
ω
2
) o
)
----------------------------------------
– t
–
ω ]
P b
=
[ (
15
– 0
) ]
=
608.6 watts
Note that this is 8.1% of rated power and is less than the maximum drive limit of 150% current limit. This calculation is the result of
and determines the peak power that must be dissipated by the Dynamic
Brake Resistor.
Average Braking Power = P av
=
( t
3
– t
2
) t
4
P
-----
2
( ω b
+
ω b
ω )
P av
=
15
-----
40
608.6
------------
2
186.92
+ 0
------------------------
186.92
= 114.1 watts
This is the result of calculating the average power dissipation as outlined in
. Verify that the sum of the power ratings of the Dynamic Brake
Resistors chosen in
Step 4 is greater than the value calculated in
Refer to
to determine the continuous power rating of the
resistor in the given drive frame you are using. You will need this number to determine the Percent Average Load and the Percent Peak
Load.
Percent Average Load
=
AL
=
100
×
P
--------
P av db
AL
=
100
×
114.1
------------
285%
40
=
This is the result of the calculation outlined in
plotted at the decel time of the application moving up vertically to this percentage.
2-11
Percent Peak Load
=
PL
=
100
×
P
--------
P db
PL
=
100
×
608.6
------------
40
=
1521%
This is the result of the calculation outlined in
plotted at zero seconds moving up vertically to this percentage.
Figure 2.2 Resistor Power Curve
2000
1800
1600
1400
1200
1000
800
3000
2800
2600
2400
2200
PL (Peak Percent Load) = 1521%
600
AL (Average Percent Load) = 285%
400
200
0
Decel Time = 15.0 Seconds
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Decel Time (Seconds)
AL and PL are plotted and connected with a dotted line. This is the Motor
Power Curve. If any portion of this curve lies to the right of the constant temperature power curve of the Dynamic Brake Resistor, the resistor element temperature will exceed the operating temperature limit. The drive will protect the resistor and shut down the Chopper transistor. The drive will then likely trip on an overvoltage fault.
2-12
Notes:
Section
3
Evaluating the Capability of the Internal Dynamic Brake Resistor
Record the values calculated in
AL =
PL
= t
3
– t
2
=
PowerFlex 70 Drives
Find the correct Figure for your PowerFlex 70 drive rating.
Drive Voltage
240
240
240
480
480
480
Frame(s)
A and B
C
D
A and B
C
D
Figure Number
1. Plot the point where the value of AL (Average Load), calculated in
Step 5 , and the desired deceleration time (t
3
– t
2
) intersect.
2. Plot the value of PL (Peak Load), calculated in
, on the vertical axis (0 seconds).
3. Connect PL at 0 seconds and AL at (t
3
– t
2
) with a straight line. This line is the power curve described by the motor as it decelerates to minimum speed.
If the power curve lies to the left of the constant temperature power curve of the Dynamic Brake Resistor, then there is no problem with the intended application. If any portion of the power curve lies to the right of the constant temperature power curve of the Dynamic Brake Resistor, then there is an application problem. The Internal Dynamic Brake
Resistor will exceed its rated temperature during the interval that the transient power curve is to the right of the resistor power curve capacity.
3-2
Figure 3.1 PowerFlex 70 – 240 Volt, A and B Frames
3000
2800
2600
2400
2200
2000
1800
1600
1400
240A/B
1200
1000
800
600
400
200
0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Decel Time (Seconds)
Figure 3.2 PowerFlex 70 – 240 Volt, C Frame
3000
2800
2600
2400
2200
2000
1800
1600
240C
1400
1200
1000
800
600
400
200
0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Decel Time (Seconds)
3-3
Figure 3.3 PowerFlex 70 – 240 Volt, D Frame
3000
2800
2600
2400
2200
2000
1800
1600
1400
240D
1200
1000
800
600
400
200
0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Decel Time (Seconds)
Figure 3.4 PowerFlex 70 – 480 Volt, A and B Frames
3000
2800
2600
2400
2200
2000
1800
1600
480A/B
1400
1200
1000
800
600
400
200
0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Decel Time (Seconds)
3-4
Figure 3.5 PowerFlex 70 – 480 Volt, C Frame
3000
2800
2600
2400
2200
2000
1800
1600
1400
480C
1200
1000
800
600
400
200
0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Decel Time (Seconds)
Figure 3.6 PowerFlex 70 – 480 Volt, D Frame
3000
2800
2600
2400
2200
2000
1800
1600
480D
1400
1200
1000
800
600
400
200
0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Decel Time (Seconds)
Section
4
How to Select an External Dynamic Brake Resistor
In order to select the appropriate External Dynamic Brake Resistor for your application, the following data must be calculated.
Peak Regenerative Power
(Expressed in watts of power.)
This value is used to determine the maximum resistance value of the
Dynamic Brake Resistor. If this value is greater than the maximum imposed by the peak regenerative power of the drive, the drive can trip off due to transient DC bus overvoltage problems.
Table 4.A Minimum Dynamic Brake Resistance for PowerFlex 70 Drives
Drive Voltage
230
Frame
A
Minimum External Resistance (Ohms 10%)
32.9
230
230
230
460
B
C
D
A
32.9
28.7
21.7
63.4
460
460
460 (15HP)
460 (20HP)
D
D
B
C
63.4
71.1
42.3
29.1
Power Rating of the Dynamic Brake Resistor
The average power dissipation of the regenerative mode must be estimated and the power rating of the Dynamic Brake Resistor chosen to be greater than the average regenerative power dissipation of the drive.
4-2
Record the Values Calculated in Section 2
P b
=
P av
=
Calculate Maximum Dynamic Brake Resistance Value
R db1
=
0.9
×
V
2
P b
R db1
= Maximum allowable value for the dynamic brake resistor
(ohms)
V d
P b
= DC bus voltage the chopper module regulates to
(375V DC or 750V DC)
= Peak breaking power calculated in Section 2:
(watts)
Calculate Maximum Dynamic Brake Resistance:
R db1
=
0.9
[
× ( ooooooooo ooooooooo
]
)
2
-----------------------------------------------
Record Maximum Dynamic Brake Resistance:
R db1
=
The choice of the Dynamic Brake resistance value should be less than the value calculated in this step. If the value is greater, the drive can trip on DC bus overvoltage. Do not reduce P b
by any ratio because of estimated losses in the motor and inverter. This has been accounted for by an offsetting increase in the manufacturing tolerance of the resistance value and the increase in resistance value due to the temperature coefficient of resistor element.
4-3
Select Resistor
Select a resistor bank from
or
or your resistor supplier that has:
• a resistance value that is less than the value calculated (R db1 in ohms)
• a resistance value that is greater than the minimum resistance listed in
• a power value that is greater than the value calculated in
(P av
in watts)
!
ATTENTION: The internal dynamic brake IGBT will be damaged if the resistance value of the resistor bank is less than the minimum resistance value of the drive. Use
to verify that the resistance value of the selected resistor bank is greater than the minimum resistance of the drive.
4-4
110
110
85
85
110
110
110
110
Ohms
154
154
154
154
154
154
59
59
59
59
85
85
85
85
59
59
Watts
182
242
408
604
610
913
255
338
570
845
850
1278
326
438
730
1089
1094
1954
473
631
1056
1576
1577
2384
Table 4.B Resistor Selection for 240V AC Drives
Catalog
Number
222-1A
222-1
225-1A
225-1
220-1A
220-1
222-2A
222-2
225-2A
225-2
220-2A
220-2
222-3A
222-3
225-3A
220-3A
225-3
220-3
222-4A
222-4
225-4A
225-4
220-4A
220-4
32
32
20
20
32
32
32
32
Ohms
45
45
45
45
45
45
20
20
20
20
Watts
617
827
1378
2056
2066
3125
875
1162
1955
2906
2918
4395
1372
1860
3063
4572
4650
7031
Catalog
Number
222-5A
222-5
225-5A
220-5A
225-5
220-5
222-6A
222-6
225-6A
225-6
220-6A
220-6
222-7A
222-7
225-7A
220-7A
225-7
220-7
181
181
181
181
237
237
181
181
237
237
237
237
342
342
342
342
439
439
342
342
439
439
439
439
Ohms
615
615
615
615
615
615
1577
2373
2068
2055
620
822
3108
1385
1096
1088
435
734
473
628
1057
1570
Watts
242
404
602
605
915
180
254
339
568
847
848
1281
329
1645
Table 4.C Resistor Selection for 480V AC Drives
440-4A
440-4
440-5A
445-5
442-5A
442-5
440-5
445-5A
440-3A
445-3
442-3
445-3A
442-4A
442-4
445-4A
445-4
Catalog
Number
442-1
445-1A
440-1A
445-1
440-1
442-1A
442-2A
442-2
445-2A
445-2
440-2A
440-2
442-3A
440-3
29
29
29
29
44
44
29
29
44
44
44
44
56
56
56
56
81
81
56
56
81
81
81
81
Ohms
128
128
128
128
128
128
440-9
442-9A
442-10
445-10A
440-10A
445-10
440-10
442-10A
440-8
445-8
445-8A
442-8
442-9
445-9A
445-9
440-9A
Catalog
Number
442-6A
442-6
445-6A
445-6
440-6A
440-6
440-7A
440-7
445-7
442-7
442-7A
445-7A
440-8A
442-8A
12784
2561
5130
8487
12667
12826
19396
3800
10045
6642
4490
2657
3381
5720
8454
8537
Watts
874
1162
1951
2906
2912
4395
4629
6944
4592
1837
1389
3102
6702
2010
4-5
4-6
Notes:
To contact Drives Technical Support . . .
Tel: (1) 262 512-8176, Fax: (1) 262 512-2222
Email: [email protected]
Online: www.ab.com/support/abdrives
Reach us now at www.rockwellautomation.com
Wherever you need us, Rockwell Automation brings together leading brands in industrial automation including Allen-Bradley controls,
Reliance Electric power transmission products, Dodge mechanical power transmission components, and Rockwell Software. Rockwell Automation's unique, flexible approach to helping customers achieve a competitive advantage is supported by thousands of authorized partners, distributors and system integrators around the world.
Americas Headquarters, 1201 South Second Street, Milwaukee, WI 53201-2496, USA, Tel: (1) 414 382-2000, Fax: (1) 414 382-4444
European Headquarters SA/NV, Boulevard du Souverain 36, 1170 Brussels, Belgium, Tel: (32) 2 663 0600, Fax: (32) 2 663 0640
Asia Pacific Headquarters, 27/F Citicorp Centre, 18 Whitfield Road, Causeway Bay, Hong Kong, Tel: (852) 2887 4788, Fax: (852) 2508 1846
Publication PFLEX-SG001A-EN-P – March 2001
Copyright 2001 Rockwell International Corporation. All rights reserved. Printed in USA.
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