Converteam ALSPA MV3DB Series User manual

Dynamic Braking
ALSPA MV3000e
Dynamic Braking Units MV3DB Series
Publication No. T1684EN Rev. 0005 (07/06)

SAFETY INSTRUCTIONS
Care has been taken with the design of this product to ensure that it is safe. However, in common with all
products of this type, misuse can result in injury or death. Therefore, it is very important that the instructions
in this manual and on the product are observed during transportation, commissioning, operation,
maintenance and disposal.
This technical manual should be regarded as part of the product. It should be stored with the product and
passed on to any subsequent owner or user.
Local safety laws and regulations must always be observed.
Persons working on the product must be suitably skilled and should have been trained in that work for
these products.
The product is a component designed for incorporation in installations, apparatus and machines.
The product must not be used as a single item safety system. In applications where maloperation of the
product could cause danger, additional means must be used to prevent danger to persons.
Product approvals and certifications will be invalidated if the product is transported, used or stored outside
its ratings or if the instructions in this manual are not observed.
Third party approvals to safety standards UL 508C and CSA C22.2 No 14 are marked on the product.
In the European Union:
•Products within the scope of the Low Voltage Directive, 73/23/EEC as amended are CE marked.
•The product complies with the essential protection requirements of the EMC directive 89/336/EEC
as amended, when installed and used as described in this manual. The requirements of the EMC
Directive should be established before any installation, apparatus or machine which incorporates
the product is taken into service.
•A machine should not be taken into service until the machine has been declared in conformity
with the provisions of the Machinery (Safety) Directive, 98/37/EEC.
CHANGES FROM PREVIOUS EDITION
Publication No. T1684EN Rev.0005 (07/06)
©2006 CONVERTEAM UK LIMITED
Revision 0004 Warning texts revised.
References to other manuals revised.
Revision 0005 Company Name change

MV3DB Series DB Units Documentation Structure
(07/06) ALSPA MV3000e Dynamic Braking Units Page i
PLANNING
&
DB UNIT SELECTION
SECTION 4
COMPREHENSIVE
INSTRUCTIONS FOR
INSTALLATION IN
BASIC DRIVE
MODULES
INSTALLATION
COMMISSIONING
SECTION 5
COMMISSIONING
PROCEDURE
+
DETAILED
DESCRIPTION OF
ASSOCIATED DRIVE
PARAMETERS
MAINTENANCE
AND
DIAGNOSTICS
SECTIONS 6 & 7
SIMPLE MAINTENANCE
+
DETAILED
DIAGNOSTIC
INFORMATION
SPARES
&
DISPOSAL
THIS MANUAL
(T1684EN) DB UNIT
STAGES OF USE
SELECTION OF
BRAKING RESISTOR
SECTION 3
DETAILED
INSTRUCTIONS FOR
SELECTION OF
BRAKING RESISTOR
SECTIONS 1 - 3
SPECIFICATIONS AND
OTHER DATA
SECTIONS 8 & 9
USER-REPLACEABLE
SPARES
+
SAFE DISPOSAL
INSTRUCTIONS

Overview MV3DB Series DB Units
ALSPA MV3000e Dynamic Braking Units (07/06)
Page ii
OVERVIEW
Section Page
1. Introduction ...................................................................................................................... 1-1
Introduces the Dynamic Braking Manual and the ALSPA MV3000e Dynamic
Braking Units (DB Units). A table shows the complete range of DB Units available
for MV3000e drives.
2. Specifications................................................................................................................... 2-1
Provides electrical and mechanical specifications for all MV3000e DB Units, also
weights and miscellaneous data common to all the units, such as derating
information.
3. System Design...................................................................................................................3-1
Contains a functional description of MV3000e DB Units and application specific
information to assist with system design, including the selection and protection of
braking resistors, with examples and suggested circuits. Topics covered include the
layout of braking components with regard to EMC requirements and wiring
segregation.
4. Installation ........................................................................................................................ 4-1
Explains how to properly install a DB Unit into a drive and how to install proprietary
Converteam braking resistors.
5. Commissioning ................................................................................................................ 5-1
Explains how to commission a DB Unit and how to configure a drive to operate with
a DB Unit and braking resistor.
6. Preventive Maintenance .................................................................................................. 6-1
Simple maintenance procedures for keeping the DB Unit serviceable.
7. Diagnostics....................................................................................................................... 7-1
What to do if the drive indicates that the DB Unit or the braking resistor has caused
a Warning or Trip to occur. Provides diagnostic hints to help find possible faults.
Refers to the Getting Started manual for information to display Warning and Trip
codes, to view a history of any previous incidents which may help with diagnosis
and to reset drive trips.
8. Spare Parts ........................................................................................................................8-1
Lists any spare parts required for user repair.
9. Disposal ............................................................................................................................ 9-1
Provides disposal instructions for the DB Unit.

MV3DB Series DB Units Contents
(07/06) ALSPA MV3000e Dynamic Braking Units Page iii
TABLE OF CONTENTS
Section Page
1. Introduction .................................................................................................................................1-1
1.1 About this Manual .........................................................................................................................1-1
1.2 About the ALSPA MV3000e Dynamic Braking Unit......................................................................1-1
1.3 Range of DB Units covered by this Manual..................................................................................1-2
1.4 Range of Standard Braking Resistors supplied by Converteam ..................................................1-2
1.5 Identity Codes...............................................................................................................................1-2
1.6 Use of Metric Units........................................................................................................................1-2
1.7 Customer Support and Training....................................................................................................1-3
1.8 Associated Publications................................................................................................................1-3
2. Specifications..............................................................................................................................2-1
2.1 Electrical Specification of DB Units and Standard Braking Resistors...........................................2-1
2.2 Duty Cycle.....................................................................................................................................2-2
2.3 Data Common to all DB Units.......................................................................................................2-2
2.4 Safety Standards...........................................................................................................................2-3
2.5 Illustration of Ratings.....................................................................................................................2-4
3. System Design ............................................................................................................................3-1
3.1 Introduction ...................................................................................................................................3-1
3.2 Functional Description...................................................................................................................3-1
3.3 Standard Braking Resistor Selection............................................................................................3-1
3.4 Alternative Braking Resistor Selection..........................................................................................3-2
3.5 Calculation for Alternative Resistors.............................................................................................3-2
3.5.1 Calculation Based on Power....................................................................................................3-2
3.5.2 Calculation Based on Inertia....................................................................................................3-3
3.6 Equivalence of Duty Cycles ..........................................................................................................3-4
3.6.1 For braking times longer than 18 seconds:..............................................................................3-4
3.6.2 For braking times less than 18 seconds: .................................................................................3-5
3.7 Braking Resistor Cable Selection .................................................................................................3-5
3.8 Resistor Protection........................................................................................................................3-6
3.8.1 Internal Protection....................................................................................................................3-6
3.8.2 External Protection...................................................................................................................3-7
3.9 Cabinet layout and EMC...............................................................................................................3-8
4. Installation ...................................................................................................................................4-1
4.1 Introduction ...................................................................................................................................4-1
4.2 Receipt of Equipment....................................................................................................................4-1
4.2.1 Inspection.................................................................................................................................4-1
4.2.2 Storage.....................................................................................................................................4-1
4.2.3 Handling...................................................................................................................................4-1
4.3 Installing the DB Unit.....................................................................................................................4-2
4.3.1 Cable Lugs and Recommended Torque Settings....................................................................4-2
4.3.2 Access to Drive Components...................................................................................................4-3
4.3.3 Installation to Frame Size 3 Drives..........................................................................................4-4
4.3.4 Installation to Frame Size 4 Drives........................................................................................4-10
4.3.5 Installation to Frame Size 6 Drives........................................................................................4-14
4.3.6 Installation to Frame Size 7 Drives........................................................................................4-18
4.4 Installing the Braking Resistor ....................................................................................................4-22
5. Commissioning ...........................................................................................................................5-1
5.1 Installation Assumptions ...............................................................................................................5-1
5.2 Commissioning Procedure............................................................................................................5-1
5.2.1 Mechanical Checks..................................................................................................................5-1
5.2.2 Power Connections..................................................................................................................5-1
5.2.3 Procedure.................................................................................................................................5-1
5.3 Drive Parameters..........................................................................................................................5-2
5.4 Dynamic Brake Status Flags.........................................................................................................5-4

Contents MV3DB Series DB Units
ALSPA MV3000e Dynamic Braking Units (07/06)
Page iv
6. Preventive Maintenance .............................................................................................................6-1
6.1 Tools and Equipment Required.....................................................................................................6-1
6.2 Maintenance Schedules................................................................................................................6-1
6.2.1 Access to Equipment ...............................................................................................................6-1
6.2.2 Monthly Servicing.....................................................................................................................6-1
6.2.3 Annual Servicing ......................................................................................................................6-1
7. Diagnostics..................................................................................................................................7-1
7.1 Fault monitoring.............................................................................................................................7-1
7.2 Warnings .......................................................................................................................................7-1
7.3 Trips...............................................................................................................................................7-1
8. Spare Parts...................................................................................................................................8-1
9. Disposal........................................................................................................................................9-1
Index
Support

MV3DB Series DB Units 1. Introduction
(07/06) ALSPA MV3000e Dynamic Braking Units Page 1-1
1. Introduction
1.1 About this Manual
This Dynamic Braking Manual provides a competent user trained in electrical installation
practice with sufficient information to safely install, commission, maintain and dispose of an
ALSPA MV3000e Dynamic Braking (DB) Unit. The manual should be read in conjunction with
the relevant ALSPA MV3000e Getting Started Manual.
This manual should be regarded as part of the ALSPA MV3000e DB Unit. It should be retained
for the life of the product and should be passed on to any subsequent owner or user.
To use a ALSPA MV3000e DELTA system configured with a DB Unit, refer to T1689, the
Technical Manual for MV3000e DELTA.
1.2 About the ALSPA MV3000e Dynamic Braking Unit
The DB Units described in this manual are intended only to be used when installed within the
associated ALSPA MV3000e MicroCubicle™- style drive and must not be used in any other
manner.
The DB Unit is used in conjunction with an externally mounted braking resistor, to dissipate
kinetic energy stored in a motor and its load. This is regenerated into the ALSPA MV3000e
drive during deceleration or when the load is overhauling. The drive monitors the DC link
voltage and uses the DB Unit to switch the braking resistor into circuit when the voltage
exceeds a pre-set level.
All DB Units are mounted within the MicroCubicle™, and are powered and controlled by the
drive. Braking functions may be configured using parameters which are described in Section 5
(Commissioning).
A typical DB Unit is illustrated in Figure 1-1.
Figure 1-1 A typical DB Unit

1. Introduction MV3DB Series DB Units
ALSPA MV3000e Dynamic Braking Units (07/06)
Page 1-2
1.3 Range of DB Units covered by this Manual
Table 1-1 shows the full range of DB Units available for MV3000e drives. There is one DB Unit
for each frame size at each available supply voltage rating. Electrical data, dimensions and
weights are provided in Section 2.
Table 1-1 – Range of DB Units available
Drive Supply Voltage
Drive
Frame
Size 380 V – 440 V 460 V – 525 V 575 V – 690 V
3 MV3DB045S5 MV3DB045S5 N/A
4 MV3DB092S5 MV3DB092S5 MV3DB061S6
6 MV3DB247S5 MV3DB247S5 MV3DB185S6
7 MV3DB391S5 MV3DB391S5 MV3DB246S6
1.4 Range of Standard Braking Resistors supplied by Converteam
Converteam produces a range of standard braking resistors designed to allow each internal
DB Unit to produce the maximum possible braking effort. Section 2.1 shows the braking
resistor model number associated with each DB Unit. The maximum permitted sizes of resistor
connecting cables are given in Section 3.7.
Instruction Sheet T1947 provides detailed installation instructions for these resistors.
1.5 Identity Codes
The code used to identify DB Units is explained in Figure 1-2 below. The figure shows the
code for a standard duty DB Unit rated at 92 Amps and with a maximum supply voltage of 525
V.
MV3DB092S5
A
LSP
A
MV3000
Series
Current
Ra ti n g (Am p s)
Dynamic
Brake Duty
Ra ti n g Voltage
Grade
Figure 1-2 DB Unit identity code
1.6 Use of Metric Units
The ALSPA MV3DB range of DB Units has been designed to IEC standards using SI units. In
this manual approximate values for inches, lb and hp are also included for convenience.

MV3DB Series DB Units 1. Introduction
(07/06) ALSPA MV3000e Dynamic Braking Units Page 1-3
1.7 Customer Support and Training
Converteam provides comprehensive telephone technical support, application planning,
service and customer training.
Contact Converteam at the address and telephone numbers shown at the end of this manual.
1.8 Associated Publications
Various ALSPA MV3000e Getting Started Manuals for Converteam
MicroCubicle™ Drives
These manuals provide competent users trained in electrical installation practice
with sufficient information to safely install, commission, operate, maintain and
dispose of simple MicroCubicle™ drive installations.
T1679 ALSPA MV3000e Software Technical Manual
This manual contains detailed technical information to enable a competent user
trained in drives to safely configure the ALSPA MV3000e drives for specific
applications. It includes full descriptions of the menu structure and parameters, also
the serial communications systems.
T1947 ALSPA MV3DBR Series Braking Resistors
This Instruction Sheet provides detailed instructions for installing braking resistors
produced by Converteam.

1. Introduction MV3DB Series DB Units
ALSPA MV3000e Dynamic Braking Units (07/06)
Page 1-4
This page intentionally left blank

MV3DB Series DB Units 2. Specifications
(07/06) ALSPA MV3000e Dynamic Braking Units Page 2-1
2. Specifications
2.1 Electrical Specification of DB Units and Standard Braking Resistors
General specifications for the DB Units and standard braking resistors are given in Table 2-1.
Default values for the braking voltage – the voltage at which the DB Unit switches the resistor
into circuit – are given in Table 2-2.
Table 2-1 – Electrical specifications for the DB Unit and the required standard braking resistor
DB Unit Suitable Braking Resistor*
Used with drives Resistance Standard Resistor from
Converteam
Model Frame
size
Nominal
ac voltage
grade
Volts
Nominal
Current
Amps
Nominal
Power during
18 seconds
ON time
kW
Minimum
Ohms
Maximum
(to achieve
nominal
power)
Ohms Name Resistance
Ohms
MV3DB045S5 3 400 45 28.10 13.6 16.6 MV3DBR045S4 13.6
" 3 480 38 28.30 15.3 23.6 MV3DBR038S5 15.3
MV3DB092S5 4 400 92 57.00 6.8 8.21 MV3DBR092S4 6.8
" 4 480 76 56.70 7.6 11.8 MV3DBR076S5 7.6
MV3DB061S6 4 690 61 56.70 11.0 20.3 MV3DBR061S6 11.0
MV3DB247S5 6 400 247 153.30 1.6 3.1 MV3DBR247S4 2.6
" 6 480 231 171.70 1.8 3.9 MV3DBR231S5 3.3
MV3DB185S6 6 690 185 171.70 3.7 6.7 MV3DBR185S6 5.1
MV3DB391S5 7 400 391 241.9 1.6 1.9 MV3DBR391S4 1.6
" 7 480 308 228.9 1.8 2.9 MV3DBR308S5 1.8
MV3DB246S6 7 690 246 228.9 3.7 5.0 MV3DBR246S6 3.7
* The chosen resistor must not be less than the minimum resistor value given in Table 2-1,
including its manufacturing and temperature related tolerances. If the rated braking power
given in Table 2-1 is required, the chosen resistor should not exceed the maximum resistance
value given in Table 2-1, including its manufacturing and temperature related tolerances.
If the application does not require the full nominal power of the DB Unit, a braking resistor may
be used which has a higher ohmic value.
Notes: 1. Refer to Section 3 (System Design) for notes on the calculation of the braking power and
for a typical application.
2. Physical dimensions of Converteam resistors are provided with the product.
Table 2-2 Default braking voltage
Nominal ac voltage
grade of drive
Volts
Default *
braking voltage
Volts
400 732
480 846
600/690 1118
* Drive dependent. Can be adjusted in
drive Menu 23.

2. Specifications MV3DB Series DB Units
ALSPA MV3000e Dynamic Braking Units (07/06)
Page 2-2
2.2 Duty Cycle
The rated Duty Cycle is 18 seconds ON per 3 minutes. This is illustrated in Figure 2-1.
During the 18 sec ON time, Nominal kW quoted in Table 2-1 should not be exceeded.
t2 =
162 seconds
OFF
t1 =
18 seconds
ON
Duty Cycle = t3 = 3 minutes
Repeat
Average Regenerative Power
Nominal kW
(Table 2-1)
2.3 Data Common to all DB Units
Table 2-3 Environment
Storage Altitude (maximum)
Temperature range
Relative humidity
3000 m
–25oC to +55oC (–13oF to +130oF)
5% to 95%, non-condensing
Transport Altitude (maximum)
Temperature range
Relative humidity
Vibration, drop
Overland 3000 m. Withstands air transport
pressurised to ≡3000 m (maximum)
–25oC to +70oC (–13oF to +158oF)
≤95%, non-condensing
IEC 60721-3-2 Class 2M1
Operating Altitude (maximum)
Temperature range
Relative humidity
Vibration
Cooling air
Ingress protection
Resistor acoustic
noise
1000 m, 1000 m to 2000 m with derating
0oC to 40oC (+32oF to +104oF);
40oC to 50oC (+104oF to +122oF) with derating
2.5% per oC. Refer to Table 2-1.
5% to 95%, non-condensing
IEC 60721-3-3 Class 3M1 & EN50178
As per drive
IP20 when fitted
< 70 dB(A)
Figure 2-1 Rated braking duty cycle

MV3DB Series DB Units 2. Specifications
(07/06) ALSPA MV3000e Dynamic Braking Units Page 2-3
Table 2-4 Common electrical data
Nominal Supply Voltage 400 V, 480 V, 600/690 V 3-phase, as
selected
Rated Duty 18 seconds at nominal power, repeating
every 3 minutes
Switching Frequency Automatic, load dependent, 1.5 kHz max.
Rated Lifetime 200,000 cycles at rated duty.
Protection Output short circuit protection + Indication*
Thermal overload protection + Indication*
* Provided via Drive parameters
Current overload protection (in the event of
fitting an unsuitable resistor)
Configurable I2T protection for braking
resistor
DB Unit Fitted Status Flag 54
DB Resistor OK Status Flag 55
DB Resistor I2T
Remaining Drive parameter 23.07
DB Resistor
Overtemperature
Warning
Warning Code 104
DB Resistor
Overtemperature
Trip
Trip Code 67
DB Unit Trip Trip Code 151
Status Signals
DB Unit
Overtemperature Trip Code 152
Table 2-5 Weights (unboxed)
Frame Size 3 4 6 7
Weight kg (lb) 1.5 (3) 3.5 (7.5) 6.5 (14.5) 6.5 (14.5)
2.4 Safety Standards
The DB Unit is designed to comply with the requirements of the following:
EN 50178 Electronic equipment for use in power installations.
ANSI/UL 508C Power conversion equipment, as marked on unit.
CAN/CSA C22.2-14 Industrial equipment, Industrial products.

2. Specifications MV3DB Series DB Units
ALSPA MV3000e Dynamic Braking Units (07/06)
Page 2-4
2.5 Illustration of Ratings
This section illustrates the ability of the DB Units to absorb the energy from inertial loads
during deceleration to zero speed. For speed reductions from one speed to another (not zero)
refer to Section 3.4.
Figures 2-2 to 2-4 show the time taken to brake a given inertia from a typical speed of 1500
r/min to zero speed, for DB Units operating at 400 V, 480 V and 690 V nominal supply volts,
using the standard Converteam braking resistors shown in Table 2-1. It is assumed that the
braking torque during deceleration is constant.
•If the initial speed is not 1500 r/min, the braking time to zero can be found by using the
graph to find the braking time graph
tfor 1500 r/min and scaling by the following formula:
where 1
t= actual braking time
2
N= initial speed
•Inertia is shown in kg m2.
1 kg m2= 23.73 lb ft2.
Figure 2-2 Stopping times from 1500 r/min at 400 V supply voltage
2
2
2
11500
N
tt graph ×=
0
2
4
6
8
10
12
14
16
18
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Total Inertia (kgm
2
)
Braking time from 1500 r/min (seconds)
MV3DB045S5 MV3DB092S5
MV3DB247S5 MV3DB391S5

MV3DB Series DB Units 2. Specifications
(07/06) ALSPA MV3000e Dynamic Braking Units Page 2-5
Figure 2-3 Stopping times from 1500 r/min at 480 V supply voltage
Figure 2-4 Stopping times from 1500 r/min at 690 V supply voltage
0
2
4
6
8
10
12
14
16
18
0 102030405060708090100110120130140150160170
Total Inertia (kgm
2
)
Braking time from 1500 r/min (seconds)
MV3DB061S6
MV3DB185S6 MV3DB246S6
0
2
4
6
8
10
12
14
16
18
0 102030405060708090100110120130140150160170
Total Inertia (kgm
2
)
Braking time from 1500 r/min (seconds)
MV3DB045S5 MV3DB092S5
MV3DB247S5
MV3DB391S5

2. Specifications MV3DB Series DB Units
ALSPA MV3000e Dynamic Braking Units (07/06)
Page 2-6
This page intentionally left blank

MV3DB Series DB Units 3. System Design
(07/06) ALSPA MV3000e Dynamic Braking Units Page 3-1
3. System Design
3.1 Introduction
This section contains a functional description of the ALSPA MV3000e DB Unit and application
specific information to assist with system design.
3.2 Functional Description
Under motor braking conditions, the rotational energy of the motor is transferred back to the
drive causing the internal DC link voltage to rise. Therefore the rate of deceleration of the
motor is limited by the amount of energy that the drive can absorb. By fitting a DB Unit and
braking resistor as shown in Figure 3-1, the drive will be able to dissipate excess energy from
the DC link and hence greatly increase the maximum rate of motor deceleration.
Figure 3-1 DB Unit function
The ALSPA MV3000e DB Unit is fitted within the drive and is controlled by the same
microprocessor that controls the inverter, allowing the MV3000e to produce the maximum
possible dynamic motor performance. Additionally, the internal interface between the DB Unit
and the microprocessor provides automatic DB Unit detection, full fault diagnostics and allows
simple software set-up for advanced features such as braking resistor protection.
3.3 Standard Braking Resistor Selection
Converteam produces a range of standard braking resistors designed to allow each internal
DB Unit to produce the maximum possible braking effort. Section 2.1 shows the braking
resistor model number associated with each DB Unit. The maximum permitted sizes of resistor
connecting cables are given in Section 3.7.
If the braking effort provided by the standard resistor is not sufficient, the user may need to
select an external DB Unit with a higher rating or an Active Front End product
– refer to Converteam.
Rectifier Inverter
Control
Braking
Resistor
DB Unit
DC+
DC-
RECT+
RECT-
BR
DC link
M
Mains
Supply
Basic Drive Module

3. System Design MV3DB Series DB Units
ALSPA MV3000e Dynamic Braking Units (07/06)
Page 3-2
3.4 Alternative Braking Resistor Selection
If the braking duty required is less than that given by the standard resistor (shown in Figures 2-
2 to 2-4), an alternative resistor may be selected. The following points should be noted:
1. The energy regenerated into the ac drive from the motor(s) and its load is limited to a
rate based on the drive's capability. The drive overload current limit applies when
motoring or regenerating.
2. The resistor value in ohms is usually determined by the DB unit current capability and
the maximum voltage at which it operates.
3.5 Calculation for Alternative Resistors
Where it is required to use a braking resistor other than a standard Converteam resistor as
shown in Table 2-1, the following procedure should be used. Two methods are given, one
based on a known power and the other upon a known inertia.
3.5.1 Calculation Based on Power
If the power being returned to the drive is known (e.g. overhauling load), the resistor may be
calculated as follows:
Resistance, Ω=
p
DB
P
V
R
2
where DB
V= DB operating voltage (see Table 2-2).
pP= Peak power during braking.
Alternatively, a resistor whose resistance is lower than this calculated value may be used, in
which case the DB unit will cycle on and off. However, the resistance value must not be less
than that given in Table 2-1.
The resistor should have a peak power capability equal to the power during braking and be
able to withstand this power for the braking time t1.
It should also have an average power capability given by:
Long term average power = Average power during braking 3
1
t
t
×
where 1
t= braking time
and 3
t= total on/off cycle time.
This is illustrated in Figure 3-2.

MV3DB Series DB Units 3. System Design
(07/06) ALSPA MV3000e Dynamic Braking Units Page 3-3
Total Start/Stop cycle time (t3)
Repeat
Average
Regenerative
Power
Peak Regenerative Power
time
power
t1 t2
Figure 3-2 DB resistor power dissipation
3.5.2 Calculation Based on Inertia
If the regenerative power is not known, but the inertia of the load is known, the resistance and
power rating may be calculated as follows:
Resistance, Ω
−
=)(2.91
122
1
2
NNJN tV
RDB
where DB V= DB operating voltage (see Table 2-2 in Section 2 “Specifications”)
J
= system inertia (kgm2)
1
t= braking time (seconds)
2
N= initial speed (r/min)
1
N= final speed (r/min)
Note:
J
= ))/(1( 2
ratioboxgearJJ loadmotor ×+ .
If there is no gear box, ratioboxgear = 1.
Inertia of the motor and load to be determined from the respective suppliers.
Peak power (at start of braking) = pP= JN N N
t
()
.
212
1
912
−
The resistor should have a peak power capability equal to the power during braking and be
able to withstand this power for the braking time t1.
It should also have an average power capability given by:

3. System Design MV3DB Series DB Units
ALSPA MV3000e Dynamic Braking Units (07/06)
Page 3-4
Long term average power = energy
total cycle time
=
3
2
1
2
2
4.182
)(
t
NNJ −
where t3= total stop-start cycle time in seconds.
Example:
Suppose we have an inertia of 0.9 kgm2, a top speed of 3000 r/min and we require to brake to
zero speed in 2 seconds repeated every 100 seconds.
Assume DB switching voltage is 732 V.
R = )(2.91
122
1
2
NNJN tV DB −=)03000(30009.0 27322.91 2 −××
×× = 12.07
Ω
Peak power = JN N N
t
()
.
212
1
912
−
= 22.91 3000)03000(9.0
×
×
−
×
= 44408 Watts or 44.4 kW
Long term average power =
3
2
1
2
2
4.182
)(
t
NNJ −= 1004.182 )03000(9.0 2
×
−× = 444 Watts
Current in resistor = R
VDB = 07.12
732 = 60.6 A
Hence MV3DB092S5 in frame size 4 will achieve this duty.
3.6 Equivalence of Duty Cycles
Ratings in Table 2-1 are given for a braking time of 18 seconds.
3.6.1 For braking times longer than 18 seconds:
•The graph shown in Figure 3-3 can be used to find the derating factor for the peak power.
•The long term average power must not exceed 10% of the “Nominal Power during 18
seconds ON time” given in Table 2-1.