DISTRIBUTOR Slipring Motors

Robust, efficient, innovative

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HELMKE slipring motors

 

Slipring Motors

Robust, efficient, innovative

2 HELMKE | Slipring Motors

HELMKE | Slipring Motors 3

Introduction HELMKE

A wide range of products and services

HELMKE is a leading supplier of

slipring motors from own manufacturing

or ex stock for following

applications:

••Ball mills

••Shredders

••Cement mills

••Variable speed for pump

application

Headquartered in Germany,

HELMKE has been a reputable

manufacturer and supplier of electrical

motors and variable speed

drives since 1922. Today HELMKE

offers tailored solutions for most

industrial applications. We provide

diversity and remain specialists.

We have the resources to handle

almost any size project while still

providing the personal attention

customers appreciate.

Certifications:

••J. HELMKE & Co.:

ISO 9001, ISO 14001,

RL 94/9/EG (ATEX),

IECEx, AEO

••HELMKE Orbis GmbH:

ISO 9001, AEO

••HELMKE S.à.r.l.:

ISO 9001, Saqr-ATEX

••HELMKE Orbis S.à.r.l.:

ISO 9001, Saqr-ATEX

HELMKE Slipring motors – built to last

Voltage (V) Maximum

output power

(MW)

0–1000 2

1000–13800 25

Experience and innovation

HELMKE records a long and successful

partnership with the heavy

industry. We are suppliers of motors

up to 25 MW, for the cement, petrochemical,

paper, pulp & wood, air

separation, mining and power generation

industries, with a successful

record of multiple motor deliveries

over the years.

Today we introduce our modular

and compact drives into the above

markets, aiming at maximum product

reliability, availability and cost

competitiveness.

4 HELMKE | Slipring Motors

Slipring motors or also called

wound rotor motors are the heart

in a lot of drive applications in the

high power range. They are most

commonly used in the raw material

industry like mining of ore and minerals

or in the binders industry like

cement, limestone and gypsum

in diverse technologies of crushers,

roller presses and mills but also in

large fans, pumps and conveyors.

Unfortunately, the more robust and

more economic squirrel cage induction

motor has such a specific characteristic

that makes the motor

start direct on the mains difficult

or under various circumstances

impossible. Especially during standstill

and at low speed during the

starting process they generate only

a low torque, while also requiring

the same time a very high current,

which is a multiple of the rated

motor current. So the driven working

machine, the technological process

or the upstream mains limit

the use of this simple drive concept.

A filled mill for example, needs a

very high torque at start-up, or

even a special initial break-away

torque, with a value possibly much

higher than the nominal torque of

the installed motor. The high inertia

of a filled mill leads additionally to

a long ramp-up time, so that the

high torque demand is required for

a long duration even at low speed.

If the process requires several starts

a day, then the thermal load on the

drive components is quite high and

may limit the number of start-ups.

In case of a high ratio of nominal

motor power to the ability of the

upstream mains a high overcurrent

during motor starting leads to a

strong voltage dip, which may affect

parallel consumers in their undisturbed

operation. This is notably the

case when single motors of relatively

high power are installed in a weak

network.

The design of induction motors with

wound rotor and sliprings allows

in combination with an appropriate

designed starter a starting torque

in the magnitude of the breakdown

torque of the motor, which is commonly

between two and three times

the corresponding nominal motor

torque at a starting current equal

or slightly higher than the nominal

motor current.

Under these circumstances the use

of slipring motors is often useful

or mandatory. In contrast to drive

applications with squirrel cage

motors and frequency converters

slipring motors must be oversized

for a high starting torque and

consequently do not produce unnecesarry

losses during the whole operating

time. By changing the motor

characteristic curve with the help

of external resistors in the rotor

circuit the motor (oil cooled or liquid

starter) the losses during start-up

of the motor are generated in the

starter, so that the frequency of

starts is not limited anymore from

motor side.

HELMKE | Slipring Motors 5

HELMKE product overview

Types of slipring motors and the designation

General characteristic

••Very high starting torque, two to

three times nominal torque

••Low starting current at start,

no or marginal higher than nominal

current

••No limited acceleration time and

number of starts

••No or very low torque impulses

during start depending on starter

technology

••High efficiency during continuous

operation (no converter losses)

••No special environmental conditions

required

••No harmonic distortions

••No EMI measures necessary, no

need of shielded connection cable

Type Code Examples

DOR Three phase motor with squirrel cage rotor,

surface cooled, round frame (e. g. IC411)

DKK Three phase motor with squirrel cage rotor,

air to air heat exchanger, round frame, box format

frame

DSKK Three phase motor with wounded rotor and

sliprings, air to air heat exchanger and box format

frame (e. g. IC611)

DSWK Three phase motor with wounded rotor and

sliprings, air to water heat exchanger and box

format frame (e. g. IC81W)

FDOR Three phase motor with squirrel cage rotor,

surface cooled, round frame (e. g. IC411) with

reinforced isolation for frequency converter

operation

DSOR Three phase motor with wounded rotor and

sliprings, surface cooled, round frame

CDEDOR Flame proof three phase motor with squirrel

cage rotor, surface cooled, round frame (e.g.

IC411) in combination with terminal boxes with

increased safety Ex d e IIC

6 HELMKE | Slipring Motors

HELMKE Slipring motors with brush lifting device

HELMKE product overview

Brush lifting device as an option

Most of all installed slipring motors

in the world are operated with

continuous contact of the brushes

to the sliprings. The advantage of

a slipring motor during the starting

period due to high starting torque

and low starting current turns

into a disadvantage during normal

motor operation. The motor performs

like a squirrel cage motor

but there is a constant wear of the

brushes and sliprings. This results

in reduced maintenance intervals to

avoid critical failures and downtime

of the plant. Furthermore the costs

for new brushes can easily reach

thousands of dollars during the lifetime

of the motor.

An effective provision to keep the

advantages of a slipring motor but

to avoid the descriped disadvantages

is a slipring motor with an

automatic brush lifting device. This

innovative system lifts the brushes

from the sliprings after the motor

has reached its nominal speed

and executes the short circuit of

the rotor phases in the slipring compartment.

HELMKE has successfully installed

several slipring motors with a brush

lifting device to customers world

wide. The better performance and

maintenance free operation of the

motors convinced our customers to

invest in this optional feature.

Advantages of an automatic brush

lifting device:

••No wear of brushes and sliprings

••No risk of flash overs in the

slipring compartment due to

excessive carbon dust

••No regular cleaning of slipring

compartment and brush change

••No follow-up costs for carbon

brushes

••Extended maintenance intervalls

and motor life time

HELMKE slipring motors with a

brush lifting device are ideal for all

constant speed applications like e.g.

ball mills, vertical mills, fans, crushers,

compressors etc.

The brush lifting device is available

for motor powers up to 10 MW (for

higher powers on request), all voltages

from 380 V to 13.8 kV and for

all speeds.

HELMKE | Slipring Motors 7

HELMKE locations

Offices and factories in the heart of Europe

HELMKE manufacturing and testing

For the support of its product development

program, HELMKE has

invested in the enhancement of its

engineering taskforce, as well as in

new testing and manufacturing

infrastructure.

1. Establishment of 6 MW load test field at

HELMKE France from 2013

2. New production and testing facility at

HELMKE headquarters in Germany

(3000m2, 100 t crane capacity)

2

1

8 HELMKE | Slipring Motors

fully configurable and compact,

housing and cooling modules. The

3-step road-map, undergone and

successfully completed by HELMKE:

••Use of cutting edge electromagnetic

(3) and fluid dynamics (1)

simulation calculation to enable

optimum utilization of high-end

and novel magnetic lamination,

winding insulation and carbon

brush materials: refine and reapply

9 decades of HELMKE

knowledge and experience to

the latest generation of electrotechnical

materials, nowadays

redefining the design rules for

electric motors.

••Optimize for high power density

at the maximum possible efficiency,

without jeopardizing the

longevity of critical motor components,

as the winding insulation

system or the slipring system:

a novel design-goal prioritization,

based on the concurrent market

demands and technology trends,

to be put in service through a new

series of HELMKE motor products.

••Embed all motor components in

a maximum configurable, flexible

and modular architecture. Furthermore,

plan for minimum number

of components and strict/

clear definitions of their functions

and functional interactions for

optimum reliability, manufacturing

cost and product availability,

involving short delivery time and

easy integration to OEM and

end-customer applications.

HELMKE is a renowned supplier

and manufacturer of Megawatt motors

for the heavy industry. Today

HELMKE is expanding its product

portfolio up to the power of 10 MW,

through its technology development

program for high performance, compact

and modular motor architectures

in Frame Sizes (FSs) 630 and

710. This paper gives an insight to

our latest product offerings, coming

as a result of our strategic planning

and R&D, in line to the latest market

trends and demands.

The increasing price-pressure as

well as the increasing penetration

of energy cost in the Total Cost

of Operation for Induction Motors

(IMs) in the power range from 5

to 10 MW, has further increased

requirements both in terms of quality

and competitiveness of the European

market. The latter sets in

front of the design engineers opposing

specifications: on the one hand

motor performance and efficiency

versus production cost and product

availability on the other. To confront

with the latest market demands

HELMKE has realized and successfully

completed a technology development

program aiming at the

development of state of the art

active components embedded in

Research and development of HELMKE products

Compact and modular architecture for high

performance squirrel cage and slipring motors

in frame size 630 and 710

Introduction to the product development program

HELMKE | Slipring Motors 9

1. HELMKE engineering: simulation of

dynamic fluids of the internal ventilation

of a motor

2. HELMKE engineering: simulation of

vibration effect in a cast iron housing

3. HELMKE engineering: electromagnetic

simulation between stator and rotor

lamination

1

2

3

10 HELMKE | Slipring Motors

HELMKE compact and modular architecture

As a result of the above technology venture,

HELMKE is launching today a brand-new motor

series in FS 630/710, offering a unique combination

of quality and cost competitiveness

to the market

Prototype product range

1

2

HELMKE compact and modular architecture:

(1) slipring, (2) squirrel cage execution

@ FS 630, (1 + 2) motor 3D CAD model highlighting

principle structural blocks

HELMKE | Slipring Motors 11

12 HELMKE | Slipring Motors

Technical highlights

Active components – Stator/Rotor

assemblies

Traditionally, the initial and most

important optimization item for

Megawatt Induction Motors is the

rotor assembly. Its design involves

a fine balance between opposing

structural, thermal and electromagnetic

requirements. HELMKE

offers with its rotors the welded

spider-shaft construction (1 a),

a well known and proven design for

its mechanical robustness as well

as predictable and long- lasting

mechanical performance. The cross

sectional area of the various rotor

components (and the resulting ventilation

ducts/gaps) has been calculated

for the optimum combination

of cooling (ventilation) and rotor

iron loss.

Stator design is incorporating

similar engineering values: detailed

stator slot geometry optimization,

accounting both for functional

(noise, iron loss) and manufacturing

(winding manufacturing and assembly)

costs. Bottom-up approach

in the design of the coil insulation

system in conjunction with the electromagnetic

and thermal design of

the magnetic core. Finally, detailed

calculation of clearances between

the winding heads (winding overhang)

and metallic structures of

the frame, for well-controlled and

predictable power factor and motor

efficiency (1 b).

The above developments along

with our Failure Mode and Effects

Analysis performed on the optimized

components enable HELMKE

to guarantee the reliable motor

operation for the long-run, at the

minimum total cost of operation for

its customers.

Motor frame and cooling system

The motor frame and cooling system

is separated to carefully

selected and designed modules

(building blocks), which house and

cool key components of the motor

system.

Our stator house and main cooler

structure feature a fully symmetrical

design, which allows for the free

positioning of the slipring room and

slipring cooler, thus a free selection

of the motor Drive End (DE) orientation

(2).

Furthermore, positioning of stator

and rotor TBs is also free of limitations,

as all frame components feature

modular and interchangeable

cable entries and cable paths. This

architecture utilizes the well known

benefits of structural symmetry

on motor noise and vibration, while

enables all different cable routes

and load arrangements in the field.

Additionally, the separation of the

main motor cooler from the slipring

cooler enables new possibilities to

HELMKE field engineers for the

individual fine tuning of the motor

and slipring-brush system cooling

performances, even under the most

extreme climatic conditions.

Based on the above, our customers

can benefit from a highly customized

product, designed, built, configured

and fine-tuned around their

specific application needs. Not vice

versa.

HELMKE compact and modular architecture

As a result of the above technology venture,

HELMKE is launching today a brand-new motor

series in FS 630/710, offering a unique combination

of quality and cost competitiveness

to the market

HELMKE | Slipring Motors 13

1. Opitimized active components in the core

of our products: (a) rotor CAD illustrating

the spider-shaft structure, (b) stator core

embedded in the modular frame module

2. Motor (a) slipring & slipring-frame,

(b) slipring cooler modules; can be freely

positioned around the fully symmetrical

main frame and cooler

3. Antifriction bearing assembly: locating

bearing at motor DE

1 a

2a

2 b 3

1 b

14 HELMKE | Slipring Motors

A produced HELMKE prototype: the result

of our product development program already

put in customer service

Modular and compact 4800 kW, 4160 V, 60 Hz,

1200 rpm slipring motor: (1) main frame

with assembled stator and rotor, (2) slipring

and slipring-bridge assembly, (3) machine

assembly

1 2

3

Motor bearing system

We have put in comparison all the

known antifriction bearing arrangements

and configurations. Long

experience and detailed calculation

have rendered a bearing assembly

design which uses the minimum

possible number of parts, the same

for motor DE and NDE bearings.

Design of these parts is driven

by functional safety and reliability

requirements. Our design offers

safe, fast and fail-safe assembly

and disassembly, a requirement

of paramount importance for our

customers expecting from HELMKE

motors nothing less than the minimum

downtime, repair and service

costs.

HELMKE | Slipring Motors 15

Ball mill drive for a cement plant in

Ukraine:

••Type: DSKK630-06

••4600 kW, 6000 V, 50 Hz, 6-pole

••IMB3, IP55, IC611

Special execution:

••Modification and delivery within

a very short time due to a breakdown

situation

••Shaft end adapted as per customer’s

requirement

••Terminal boxes adapted according

to customer’s requirements

••Commissioning by HELMKE technician

at site

Slipring motor for a ball mill in

Russia:

••Type: DSKK1000-06

••7000 kW, 10000 V, 50 Hz, 6-pole

••IMB3, IP55, IC616

Special execution:

••Adaptation to existing conditions

••Delivery ex stock incl. liquid starter

and oil supply system for sleeve

bearings

••Commissioning by HELMKE technician

Slipring motor for a conveyor belt in

Canada:

••Type: DSOR800-06

••1625 kW, 4160 V, 60 Hz, 6 pole

••IC511, IP55, IMB3

Special execution:

••Thermal windows in both slipring

compartment inspection covers

••Special grease for low temperature

in bearings

••Increased power of electric heating

••Special brushes for dry environment

References

www.helmke.de

This paper presents an activities

and result summary, concerning our

product development program for

compact and modular motor architectures

in FS 630/710. Throughout

this program, HELMKE has realized

extensive investment in infrastructure

and product R&D, aiming at

an optimum combination of quality,

reliability and cost competitiveness

in the final motor product.

As a result of this technology venture,

we place today in the heavy

industry market state-of-the-art

technologies in motor principle

design and engineering to offer the

minimum Total Cost of Operation

to our customers. Our prototype

modular and compact designs serve

already critical industrial applications,

further expanding our success

record in this market sector.

Benefit now from our technology

and meet our products through our