Parker NK Series User manual

1 - PVD 3664_GB_NK-November 2016.Docx
Servomotors
NK Series
Technical Manual
PVD 3664_GB

2 - PVD 3664_GB_NK-November 2016.Docx
EU DECLARATION OF CONFORMITY
We , Parker Hannifin Manufacturing France SAS
Electromechanical & Drives Division Europe
Etablissement de Longvic
4 Boulevard Eiffel - CS40090
21604 LONGVIC Cedex - France
manufacturer, with brand name Parker, declare under our sole responsibility that the products
SERVOMOTORS TYPE NK
satisfy the arrangements of the directives :
Directive 2014/35/EU : “Low Voltage Directive”, LVD
Directive 2011/65/EU : “Restriction of Hazardous Substances”, RoHS
Directive 2014/30/EU : “Electromagnetic Compatibility”, EMC
and meet standards or normative document according to :
EN 60034-1:2010/AC:2010 : Rotating electrical machines - Part 1 : Rating and performance.
EN 60034-5:2001/A1:2007 : Rotating electrical machines - Part 5 : Degrees of protection
provided by the integral design of rotating electrical machines (IP code) - Classification.
EN 60204-1:2006/AC:2010 : Safety of machinery –Electrical equipment of machines –Part 1 :
General requirements.
The product itself is not impacted by the modifications made on the latest directives.
The undersigned certify that the above mentioned model is procured in accordance with the
above directives and standards.
Further information :
SERVOMOTORS shall be mounted on a mechanical support providing good heat conduction
and not exceeding 40° C in the vicinity of the motor flange.
As NK is a kit motor, final conformance of the complete motor is under the responsibility of the
integrator.
The product must be installed in accordance with the instructions and recommendations contained in
the operating instructions supplied with the product.
NK1 C.E. Marking : March 2005 NK4 C.E. Marking : September 2002
NK2 C.E. Marking : October 2003 NK6 C.E. Marking : July 2002
NK3 C.E. Marking : November 2001 NK8 C.E. Marking : April 2004
Longvic, November 18th 2016 In the name of Parker
A. ANDRIOT
Quality Manager
Ref : DCE-NK-001rev0

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Table of Content
1. INTRODUCTION .............................................................................................................................5
1.1. Purpose and intended audience .............................................................................................5
1.2. Safety......................................................................................................................................5
1.2.1. Principle......................................................................................................................... 5
1.2.2. General Safety Rules .................................................................................................... 6
2. PRODUCT DESCRIPTION .............................................................................................................7
2.1. Quick URL...............................................................................................................................7
2.2. Overview .................................................................................................................................7
2.3. Applications.............................................................................................................................8
2.4. Motor description.................................................................................................................. 10
2.5. General Technical Data ....................................................................................................... 10
2.6. Product Code ....................................................................................................................... 11
3. TECHNICAL DATA...................................................................................................................... 12
3.1. Motor selection..................................................................................................................... 12
3.1.1. Altitude derating........................................................................................................... 12
3.1.2. Temperature derating.................................................................................................. 12
3.1.3. Thermal equivalent torque (rms torque)...................................................................... 14
3.1.4. Drive selection............................................................................................................. 16
3.1.5. Current limitation at stall conditions (i.e. speed < 3 rpm)............................................ 19
3.1.6. Peak current limitations............................................................................................... 19
3.2. NK Characteristics: Torque, speed, current, power… ......................................................... 20
3.2.1. NK data with natural cooling –Mains voltage 230V.................................................... 21
3.2.2. NK data with natural cooling –Mains voltage 400V.................................................... 22
3.2.3. NK data with water cooling –Mains voltage 400V...................................................... 22
3.2.4. Further Data with natural cooling ................................................................................ 23
3.2.5. Further Data with water cooling................................................................................... 24
3.2.6. Efficiency curves.......................................................................................................... 25
3.2.7. Electromagnetic losses................................................................................................ 33
3.2.8. Time constants of the motor........................................................................................ 34
3.2.9. Speed ripple ................................................................................................................ 36
3.2.10. Cogging torque............................................................................................................ 36
3.2.11. Rated data according to rated voltage variation.......................................................... 37
3.2.12. Voltage withstand characteristics of NK series ........................................................... 39
3.3. Dimension drawings............................................................................................................. 40
3.3.1. NK1.............................................................................................................................. 40
3.3.2. NK2.............................................................................................................................. 41
3.3.3. NK3.............................................................................................................................. 42
3.3.4. NK4.............................................................................................................................. 43
3.3.5. NK6.............................................................................................................................. 44
3.3.6. NK8.............................................................................................................................. 45
3.3.1. NK3..W ........................................................................................................................ 46
3.3.2. NK4..W ........................................................................................................................ 47
3.3.3. NK6..W ........................................................................................................................ 48
3.3.4. NK8..W ........................................................................................................................ 49
3.4. Motor mounting recommendations ...................................................................................... 50
3.4.1. Frame recommendation .............................................................................................. 50
3.4.2. Servomotor typical construction .................................................................................. 51
3.4.3. Bearings recommendation .......................................................................................... 51
3.4.4. Mechanical interfaces.................................................................................................. 52
3.4.5. Water cooled version recommendations..................................................................... 55
3.4.6. Design Compliance ..................................................................................................... 56
3.4.7. Dielectric test............................................................................................................... 56
3.4.8. Earthing ....................................................................................................................... 56
3.4.9. Minimum clearances for insulation and creepage distances....................................... 56
3.4.10. Ground continuity compliance..................................................................................... 57
3.4.11. Protection rating .......................................................................................................... 57
3.4.12. Overspeed test ............................................................................................................ 58
3.4.13. EMC Directive.............................................................................................................. 58
3.4.14. Other requirements...................................................................................................... 58

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3.5. Cooling................................................................................................................................. 59
3.5.1. Natural and fan cooled motor...................................................................................... 59
3.5.2. Water cooled motor..................................................................................................... 60
3.5.3. Additives for water as cooling media........................................................................... 61
3.5.4. Motor cooling circuit drop pressure ............................................................................. 62
3.5.5. Chiller selection ........................................................................................................... 62
3.5.6. Flow derating according to glycol concentration ......................................................... 63
3.5.7. Water cooling diagram................................................................................................. 65
3.6. Thermal Protection............................................................................................................... 67
3.6.1. Alarm tripping with PTC thermistors :.......................................................................... 67
3.6.2. Temperature measurement with KTY sensors:........................................................... 68
3.7. Power Electrical Connections .............................................................................................. 69
3.7.1. Wires sizes .................................................................................................................. 69
3.7.2. Conversion Awg/kcmil/mm²:........................................................................................ 70
3.7.3. Motor cable length....................................................................................................... 71
3.7.4. Ground connection...................................................................................................... 71
3.7.5. Motor cable.................................................................................................................. 71
3.8. Feedback system................................................................................................................. 72
3.8.1. Resolver ...................................................................................................................... 72
3.8.2. Encoder ....................................................................................................................... 77
4. COMMISSIONING, USE AND MAINTENANCE.......................................................................... 78
4.1. Instructions for commissioning, use and maintenance........................................................ 78
4.1.1. Equipment delivery...................................................................................................... 78
4.1.2. Handling ...................................................................................................................... 78
4.1.3. Storage........................................................................................................................ 78
4.2. Machine Integration.............................................................................................................. 79
4.2.1. General warnings ........................................................................................................ 79
4.2.2. Tightening torque......................................................................................................... 81
4.2.3. Rotor integration step by step ..................................................................................... 82
4.2.1. Natural cooled stator integration step by step............................................................. 84
4.2.2. Water cooled stator integration step by step............................................................... 86
4.2.3. Motor integration.......................................................................................................... 87
4.3. Resolver mounting ............................................................................................................... 93
4.3.1. Mounting step by step ................................................................................................. 93
4.3.2. Setting of the resolver.................................................................................................. 94
4.4. Electrical connections .......................................................................................................... 95
4.5. Encoder cable handling........................................................................................................ 97
4.6. Tests..................................................................................................................................... 98
4.7. Troubleshooting ................................................................................................................... 99

5 - PVD 3664_GB_NK-November 2016.Docx
1. INTRODUCTION
1.1. Purpose and intended audience
This manual contains information that must be observed to select, install, operate and
maintain PARKER NK servomotors.
The design, tests, certification, commissioning, operation and maintenance of the
equipment should be carried out by qualified personnel. A qualified person is someone
who is technically competent and familiar with all safety information and established
safety practices; with the installation process, operation and maintenance of this
equipment; and with all the hazards involved.
Reading and understanding the information described in this document is mandatory
before carrying out any operation on the motors. If any malfunction or technical
problem occurs, that has not been dealt with in this manual, please contact PARKER
for technical assistance. In case of missing information or doubts regarding the
installation procedures, safety instructions or any other issue tackled in this manual,
please contact PARKER as well.
PARKER’s responsibility is limited to its servomotors and does not encompass the
whole user’s system. Data provided in this manual are for product description only and
may not be guaranteed, unless expressly mentioned in a contract.
DANGER: PARKER declines responsibility for any accident or
material damage that may arise, if the procedures and safety
instructions described in this manual are not scrupulously followed.
1.2. Safety
1.2.1. Principle
To operate safely, this equipment must be transported, stored, handled, installed and
serviced correctly. Following the safety instructions described in each section of this
document is mandatory. Servomotors usage must also comply with all applicable
standards, national directives and factory instructions in force.
DANGER: Non-compliance with safety instructions, legal and technical
regulations in force may lead to physical injuries or death, as well as
damages to the property and the environment.

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1.2.2. General Safety Rules
Generality
DANGER: The installation, commission and operation must be performed by
qualified personnel, in conjunction with this documentation.
The qualified personnel must know the safety (C18510 authorization,
standard VDE 0105 or IEC 0364) and local regulations.
They must be authorized to install, commission and operate in accordance
with established practices and standards.
Electrical hazard
Servo drives may contain non-insulated live AC or DC components. Respect
the drives commissioning manual. Users are advised to guard against
access to live parts before installing the equipment.
Some parts of the motor or installation elements can be subjected to
dangerous voltages, when the motor is driven by the inverter , when the
motor rotor is manually rotated, when the motor is driven by its load, when
the motor is at standstill or stopped.
For measurements use only a meter to IEC 61010 (CAT III or higher).
Always begin using the highest range. CAT I and CAT II meters must not be
used on this product.
Allow at least 5 minutes for the drive's capacitors to discharge to safe
voltage levels (<50V). Use the specified meter capable of measuring up to
1000V dc & ac rms to confirm that less than 50V is present between all
power terminals and between power terminals and earth.
Check the drive recommendations.
The motor must be permanently connected to an appropriate safety earth.
To prevent any accidental contact with live components, it is necessary to
check that cables are not damaged, stripped or not in contact with a rotating
part of the machine. The work place must be clean, dry.
General recommendations :
- Check the wiring circuit
- Lock the electrical cabinets
- Use standardized equipment
Mechanical hazard
Servomotors can accelerate in milliseconds. Running the motor can lead to
other sections of the machine moving dangerously. Moving parts must be
screened off to prevent operators coming into contact with them. The
working procedure must allow the operator to keep well clear of the danger
area.
Burning Hazard
Always bear in mind that some parts of the surface of the motor can reach
temperatures exceeding 100°C.

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2. PRODUCT DESCRIPTION
2.1. Quick URL
All informations and datas are avaible on :
http://www.parker.com/eme/nk
2.2. Overview
The NKframeless servomotor are the active parts of a servo motor: a rotor and a stator.
The NK series can not be used alone and must integrated into a complete system to
provide a complete servomotor. The design, the construction, the certification and the
tests are the responsibility of the integrator.
NK servomotors Series from PARKER is an innovative direct drive solution designed
for industrial applications. NK Series brushless servomotors from Parker combine
exceptional precision and motion quality, high dynamic performances and very
compact dimensions.
A large set of torque / speed characteristics, options and customization possibilities
are available, making NK Series servomotors the ideal solution for most servosystems
applications.
Advantages
- Low cogging
- Compact dimensions and robustness
- High precision
- High motion quality
- High dynamic performances
- Higher stiffness of the system
- Simple, light and compact machine design
- no coupling systems needed
- Global cost reduction
- Increased reliability and reduced maintenance
- Integration assistance

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2.3. Applications
Medical: Blood pumps, air pump, radiology tables,…
Machine tools: Ancillary axis, spindle, axis…
Marine Submarine
Semiconductor
Hand tool: screwdriver,…
Packaging machinery
Robot applications
Special machines
Pump
Compressor
Partner of your integration :
Flexible organization and technical know-how
Assistance during mechanical integration
Assistance during mechanical system tuning
Frameless
Servomotors
Integration
Fully optimized
mechanical
system

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Examples Electric cylinder
Mains benefits:
Cost (coupling, bearings, motor front flange are deleted
and cylinder frame is simple)
Compact (40% smaller than standard cylinder)
Excellent control due to the high mechanical stiffness
(no coupling)
Lower weight (ideal for robot application)
Pump
Mains benefits:
Low cost
Compact
Simplified design
Low temperature rise

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2.4. Motor description
2.5. General Technical Data
NK1
NK2
NK3, NK4,NK6
NK8
Motor type
Permanent-magnet synchronous motor
Magnets material
Neodymium Iron Boron
Number of poles
10
Degree of
protection
IP00
Cooling
Natural cooling
Natural cooling,
Water cooled
Rated voltage
230VAC
230VAC, 400 VAC and 480 VAC
Insulation of the
stator winding
Class F according to IEC
60034-1 with potting
Class F according
to IEC 60034-1
Class F according
to IEC 60034-1
with potting
Altitude
Up to 1000m (IEC 60034-1)
(for higher altitude see §3.1.1 for derating)
Ambiant
temperature
-15°C to +40°C (IEC 60034-1)
-40°C on request
0°C to 40°C for water cooled version (IEC 60034-1)
to avoid condensation see §3.5
Storage
temperature
-20… +60°C
Connection
Cable
ROTOR
STATOR
Magnets
Rotor stack
laminations
Stator stack
laminations
Copper windings
impregnated with resin
Rotor flange for
balancing
Rivets

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2.6. Product Code
Code
N
K
3
1
0
E
A
K
R
1
0
0
0
Product Series
Motor size
1, 2, 3, 4, 6 or 8 in relation with the
motor diameter
Motor length
up to 60 depend on size
Windings variant
E: standard serial windings class F
W: serial windings class F water cooled
Feedback Sensor
A: resolver 2 poles transformation ratio = 0.5
K: without sensor
P: Hiperface DSL SIL2 encoder singleturn EKS36
Q: Hiperface DSL SIL2 encoder mutiturn SKM36
R: Hiperface encoder singleturn SKS36 (128pulses)
S: Hiperface encoder mutiturn SKM36 (128pulses)
T: Hiperface encoder singleturn SRS50 (1024pulses)
U: Hiperface encoder mutiturn SRM50 (1024pulses)
V: Endat encoder singleturn ECN1113
W: Endat encoder multiturn ECN1125
X: Commuted lines 10 poles –2048pulses
Y: sensorless series for 650S drive
Z : Special encoder
Torque / Speed Characteristics
See motor data
Unused character
Electric connection
1: flying wires
Mechanical Interface
000: Standard motor
Other: custom code

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3. TECHNICAL DATA
3.1. Motor selection
3.1.1. Altitude derating
From 0 to 1000 m : no derating
1000 to 4000 m: torque derating of 5% for each step of 1000 m for water cooled
1000 to 4000 m: torque derating of 10% for each step of 1000 m for air cooled
3.1.2. Temperature derating
3.1.2.1. Natural cooled motor
The maximal temperature for natural cooling is 40°C. But, it is possible to increase a
little bit the ambient temperature above 40°C, with a torque reduction. The following
formula gives an indicative about the torque derating at low speed. But in any case
refer to PARKER technical department to know the exact values
At low speed the torque derating is given by the following formula for an ambient
temperature > 40°C.
CCetemperaturAmbientC
deratingTorque 

105 )_145( *100[%]_
At high speed, the calculation is more complex, and the derating is
much more important.
Please refer to PARKER to know the precise data of Torque derating
according to ambient temperature at high speed for a specific motor.
Illustration: Only for example given for the NK620EAR :
Torque Derating vs. ambient temperature
75
80
85
90
95
100
105
25 30 35 40 45 50 55 60
Ambient temperature [°C]
Torque derating [%]
Torque derating at low speed [%]
Torque derating at high speed [%]

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3.1.2.2. Water cooled motor
Typical values are given with a water inlet temperature of 25°C and a temperature
gradient Inlet-Outlet of 10°C. These references lead to a winding overheating of 95°C
corresponding to a winding temperature of 120°C. Recommendations regarding
condensation issues are given at § 3.5
It is possible to increase a little bit the Inlettemperature up to 40°C, but the torquemust
be reduced. The following formula gives an indicative of the torque derating at low
speed. But in any case refer to PARKER technical department to knowthe exact values
At low speed the torque derating is given by the following formula for an water Inlet
temperature > 25°C.
CCetemperaturInletC
deratingTorque 

95 )_120( *100[%]_
At high speed, the calculation is more complex, and the derating is
much more important.
Please refer to PARKER to know the precise data of Torque derating
according to water inlet temperature at high speed for a specific motor.
Illustration: Only for example given for the NK860WAF
Torque Derating vs. ambiente temperature
90
92
94
96
98
100
102
25 30 35 40
Ambient temperature [°C]
Torque derating [%]
Torque derating at low speed [%]
Torque derating at high speed [%]
Torque Derating vs cooling temperature
Cooling temperature

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3.1.3. Thermal equivalent torque (rms torque)
The selection of the right motor can be made through the calculation of the rms torque
Mrms (i.e. root mean squared torque) (sometimes called equivalent torque).
This calculation does not take into account the thermal time constant. It can be used
only if the overload time is much shorter than the copper thermal time constant.
The rms torque Mrms reflects the heating of the motor during its duty cycle.
Let us consider:
- the period of the cycle T [s],
- the successively samples of movements icharacterized each ones by the maximal
torque Mi[Nm] reached during the duration  ti[s].
So, the rms torque Mrms can be calculated through the following basic formula:
Example:
For a cycle of 2s at 0 Nm and 2s at 10Nm and a period of 4 s, the rms torque is
Illustration :
Acceleration-deceleration torque: 10 Nm for 0,1 s.
Resistant torque: 1 Nm during all the movement.
Max-min speed: 2800 rpm during 0,2 s.
Max torque provided by the motor: 11 Nm.
rms torque: 6 Nm.
The maximal torque Midelivered by the motor at each segment iof movement is
obtained by the algebric sum of the acceleration-deceleration torque and the resistant
torque. Therefore, Mmax corresponds to the maximal value of Mi.
-20
-15
-10
-5
0
5
10
15
20
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Time [s]
Torque [Nm]
-4000
-3000
-2000
-1000
0
1000
2000
3000
4000
Speed [rpm]
motor torque [Nm] rms average torque [Nm]
speed [rpm] rms average speed [rpm]


 n
iiirms tM
T
M1
2
*
1
NmMrms 07,72*10*
4
12

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Selection of the motor :
The motor adapted to the duty cycle has to provide the rms torque Mrms at the rms
speed(*) without extra heating. This means that the permanent torque Mnavailable at
the average speed presents a sufficient margin regarding the rms torque Mrms.
(*) rms speed is calculated thanks to the same formula as that used for the rms torque.
The mean speed cannot be used (in general mean speed is equal to zero).
Only use the rms speed.
Furthermore, each Mi and speed associated Ωi of the duty cycle has to be located in
the operational area of the torque vs speed curve.
Torque
Mk
Mrms.
Mn
Mi
Ωi Ωk Ωrms Ωn Speed


 n
iiirms t
T1
2
*
1

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3.1.4. Drive selection
Drive selection depends on its rated power and its mode selection which leads to the
maximal current duration.
Please refer to the drive technical documentation for any further
information and to select the best motor and drive association.
AC890 PARKER drive example:
The rated current provided by the AC890 drive depends on its rated power and its
mode selection. “Vector mode” is used for induction motors while “Servo mode” is used
for brushless AC motors. With NK motors the power is usually < 37 kW, the rated
current corresponds to 100 %.
Power of Drive AC890 [kW]
< 37 kW
Mode
Vector mode
Servo mode
Overload capability [%]
150 % during 60 s
200 % during 4 s
Illustration:
0
5
10
15
20
25
0500 1000 1500 2000 2500 3000 3500 4000
Speed [rpm]
Torque [Nm]
100% permanent
200% during 4 s

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Example n°1 :
The application needs:
- a rms torque of 7 Nm at the rms speed of 2000 rpm,
- an acceleration torque of 12 Nm,
- a maximal speed of 2800 rpm.
Selection of the motor:
The selected motor is the type NK620EAR.
The nominal speed is equals to 3900 rpm.
The maximal speed is equals to 3900 rpm.
The torque sensitivity is equals to 1.47 Nm/Arms.
The permanent current I0of the motor is 5.31 Arms for M0=8 Nm at low speed.
The nominal current Inof the motor is 4.25 Arms for Mn=6.17 Nm at the nominal speed.
Selection of the drive:
The drive has to provide at least a permanent current equals to I0(5.31 Arms).
In order to obtain an acceleration torque of 12 Nm, the current will be about 8 Arms
(the motor data sheet shows 17 Nm with 11.3 Arms). This means that the drive has to
provide at least 8 Arms as transient current.
Therefore, we can select the drive AC890SD-53 2100 B which delivers under 400
VAC:
6 Arms as permanent current and
6*200%=12 Arms as maximal transient current during 4 s.
The drive is set with “Servo Mode”.
We also can select the drive DIGIVEX 8/16 Â which delivers under 400 VAC:
5.6 Arms as permanent current and
5.6*200%=11.3 Arms as maximal transient current during 2 s.
BRUSHLESS MOTORS BÜRSTENLOSE SERVOMOTOREN
NX620EAR NX620EAR
ELECTRONIC DRIVE (1) STEUERELEKTRONIK (1)
DIGIVEX 7.5/15 et DIGIVEX 8/16 DIGIVEX 7.5/15 et DIGIVEX 8/16
(230V) (400V) (480V)
Torque at low speed
MoNm 8
Permanent current at low speed
IoArms 5.31
Peaktorque
MpNm 26.7 --
Current for the peak torque
IpArms 21.2 --
Back emf constant at 1000 rpm (25°C)* Ke
Vrms 95.7
Torque sensitivity Kt
Nm/Arms 1.51
Winding resistance (25°C)* Rb 2.24
Winding inductance* L mH 19.2
Rotor inertia J
kgm²x10-5 98
Thermal time constant Tth min 27
Motor mass M kg 7
Voltage of the mains UR1UR2UR3
Vrms 230 400 480
Rated speed Nn1Nn2Nn3 rpm 2200 3900 4500
Rated torque Mn1Mn2Mn3 Nm 7.42 6.17 5.57
Rated current In1 In2 In3
Arms 4.99 4.25 3.89
Rated power Pn1Pn2 Pn3 W1710 2520 2620
All dataare givenin typical values under standardconditions
* Phase to phase (1) Please check the availability of this drive with 480 V
Voltages and currents are given in rms values
Characteristics are given for an optimal drive of the motor FICHE-009
Création: 04 avr 2000 Edition: 31/mars/2011 NX620EAR .a
0
2
4
6
8
10
12
14
16
18
01000 2000 3000 4000 5000
Torque in N.m
Speed in rpm

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Example n°2 :
This times; the application needs :
- a permanent torque of 5.8 Nm at low speed,
- a rms torque of 5.8 Nm at the rms speed of 1890 rpm,
- an acceleration torque of 8.8 Nm,
- a maximal speed of 2800 rpm.
Selection of the motor:
The selected motor is the type NK620EAR.
The nominal speed is equals to 3900 rpm.
The maximal speed is equals to 3900 rpm.
The torque sensitivity is equals to 1.47 Nm/Arms.
Selection of the drive:
The drive has to provide a permanent current equals to 4 Arms to obtain 5.8 Nm.
In order to obtain an acceleration torque of 8.8 Nm, the current will be of about 6 Arms
This means that the drive has to provide at less 6 Arms as transient current.
Compared to the previous example n°1, it is now possible to decrease thesize of drive.
Therefore, we can select the drive AC890SD-53 1600 B which delivers under 400
VAC:
4 Arms as permanent current and
4*200%=8 Arms as maximal transient current during 4 s.
The drive is set with “Servo Mode”.

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3.1.5. Current limitation at stall conditions (i.e. speed < 3 rpm)
Recommended reduced current at speed < 3 rpm:
00 *0.7*
2
1IIIreduced 
Warning: The current must be limited to the prescribed values. If the
nominal torque has to be maintained at stop or low speed (< 3 rpm),
imperatively limit the current to 70% of I0(permanent current at low
speed), in order to avoid an excessive overheating of the motor.
Please refer to the drive technical documentation for any further
information and to choose functions to program the drive.
3.1.6. Peak current limitations
It is possible to use the NK motor with a current higher than the permanent current.
But, to avoid any overheating, the following rules must be respected.
1) The peak currents and peak torques given in the data sheet must never be
exceeded
2) The thermal equivalent torque must be respected (§3.1.3)
3) If 1) and 2) are respected (it can limit the peak current value or duration), the
peak current duration (tp) must be limited, in addition, accordingly to the
following table (Io is the permanent current at low speed):
Ipeak/In
Ip/Io =2
Ip/Io = 3
Ip/Io =4
Ip/Io >5
NK110
tp<0.8 s
tp<0.3s
tp<0.15s
tp<0.1s
NK210
NK310
NK420
NK430
NK620
tp<1.5s
tp<0.6s
tp<0.3s
tp<0.2s
NK630
NK820
NK840
NK860
NK860V
tp<3s
tp<1.5s
not allowed
NK860W
The peak current duration is calculated for a temperature rise of 3°C
Consult us for more demanding applications.
0
1
2
3
4
0 5 10 15 20 25
Peak current/Low speed
current
Time
I/Io
tp
tc

20 - PVD 3664_GB_NK-November 2016.Docx
3.2. NK Characteristics: Torque, speed, current, power…
The torque vs speed graph below explains different intrinsic values of the next tables.
Torque
Peak Torque
Permanent
Low Speed
Torque
Rated
torque
Stall torque
3 rpm Rated Max Speed
speed speed
Rated
Power