ISSN 2307–3489 (Print), ІSSN 2307–6666 (Online)
Наука та прогрес транспорту. Вісник Дніпропетровського
національного університету залізничного транспорту, 2016, № 5 (65)
ЕЛЕКТРИЧНИЙ ТРАНСПОРТ
doi 10.15802/stp2016/83992 © L. V. Dubynets, O. L. Marenych, O. Yu. Baliichuk, A. S. Kortohus, 2016
ЕЛЕКТРИЧНИЙ ТРАНСПОРТ
UDC 62-83
L. V. DUBYNETS
1
, O. L. MARENYCH
2
, O. YU. BALIICHUK
3
, A. S. KORTOHUS
4*
1
Dep. «Electric Engineering and Electromechanics», Dnipropetrovsk National University of Railway Transport named
after Academician V. Lazaryan, Lazaryan St., 2, Dnipro, Ukraine, 49010, tel. +38 (056) 373 15 47,
ORCID 0000-0003-0319-4544
2
Dep. «Electric Engineering and Electromechanics», Dnipropetrovsk National University of Railway Transport named
after Academician V. Lazaryan, Lazaryan St., 2, Dnipro, Ukraine, 49010, tel. +38 (056) 373 15 47,
ORCID 0000-0003-3602-5851
3
Dep. «Electric Engineering and Electromechanics», Dnipropetrovsk National University of Railway Transport named
after Academician V. Lazaryan, Lazaryan St., 2, Dnipro, Ukraine, 49010, tel. +38 (056) 373 15 47,
e-mail baliichukaleksei@mail.ru, ORCID 0000-0003-0119-1446
4*
Dep. «Electric Engineering and Electromechanics», Dnipropetrovsk National University of Railway Transport named
after Academician V. Lazaryan, Lazaryan St., 2, Dnipro, Ukraine, 49010, tel. +38 (096) 256 19 65,
e-mail andrykor63@gmail.com, ORCID 0000-0001-9316-3500
ENERGY SAVING DURING OPERATION OF EQUIPMENT
WITH NON-CONTROLLED ELECTRIC DRIVE
IN LOCOMOTIVE DEPOT
Purpose. To conduct research of electric motors in order to obtain the results that will assess the degree of en-
ergy saving due to electric loss reduction in the equipment with non-controlled electric drive. Methodology. The
paper proposes an engineering method for determination of active power losses in the motors of the equipment with
non-controlled electric drive in locomotive depot during load changes on the motor shaft. It is necessary to analyse
the reduction of active power losses in the motor and the power supply network when an under-loaded motor is re-
placed with a motor having less power. Findings. After the calculations performed by the authors, it was found that
for electric motors, in case of reducing the load factor from
0,7...0,75 to 0, 4...0,5 active loss reduction after the
motor replacement for the less powerful one ranges from 0.58 kW to 2.865 kW. Also, the calculations were carried
out on the example of electric motors with a lower synchronous speed, the effect of under-loaded motor replacement
increases in terms of active power loss reduction. The greatest effect is achieved when the load factor is
0.55
l
k
≤
.
Originality. For the first time the paper outlines the issues of energy saving efficiency for the equipment with non-
controlled electric drive in locomotive depot by replacing the under-loaded motors with the less powerful ones. As
long as there is a significant amount of the considered electric drives, it may cause severe losses, taking into account
the peculiarities of their operation. Practical value. The obtained research results allow us to solve the problem of
replacement of under-loaded motors in locomotive depot equipment with the motors having less power as efficiently
as possible in terms of reducing electric losses. For instance 90-kW motor of a washing machine can be replaced
with 75-kW motor when the load factor is
0.7
l
k
≤
, this can significantly reduce the performance losses. This
method can be applied not only in locomotive depot but also for all equipment with non-controlled electric drives
that operates in under-load mode.
Keywords: electric drives; locomotive depot; energy savings; active power loss; motor load factor; AIR series
motors
54
ISSN 2307–3489 (Print), ІSSN 2307–6666 (Online)
Наука та прогрес транспорту. Вісник Дніпропетровського
національного університету залізничного транспорту, 2016, № 5 (65)
ЕЛЕКТРИЧНИЙ ТРАНСПОРТ
doi 10.15802/stp2016/83992 © L. V. Dubynets, O. L. Marenych, O. Yu. Baliichuk, A. S. Kortohus, 2016
Introduction
Energy saving is the strategic line of develop-
ment of the main branches of the economy. A sig-
nificant share of electric power consumers falls to
electric motors of various purposes, which con-
sume more than half of the energy produced
[3, 12]. There is where the largest energy saving
reserves lie in. The repair of locomotives in a depot
often involves the equipment whose electric drive
motors operate in non-controlled mode. This usu-
ally includes squirrel-cage induction motors with
power from tenth of kW to several tens of kW. For
example, dolly, which is used for repair of locomo-
tive bogies, has the electric motor with power of
0.8 kW; the electric motor of the assembly line for
locomotive axle-box repair has power of 2.2 kW;
electric motor power of the washing machine for
washing the bearings is 29.7 kW, that of washing
machine for washing the traction motors is 82 kW,
etc. [1, 16, 18].
Purpose
To conduct research in order to obtain the re-
sults that will assess the degree of energy saving
due to electric loss reduction in the equipment with
non-controlled electric drive.
Methodology
Practice shows that in real operation conditions
of this equipment, depending on the locomotive
repair technology, the load factor of many electric
drive motors is less than 50%. The drive operation
in under-load mode results in huge losses. There
are several ways to implement energy saving by
means of an industrial electric drive [1, 16, 17, 18].
In our case, the most appropriate in terms of ease
of implementation and losses is the replacement of
the powerful electric drive with that having less
power to reduce active power losses in the motor
and in the electricity network [3, 4, 17, 18]. Let us
consider the specific example, when for the pur-
pose of equipment unification the traction motor
washing machine is used for washing reduction
gear housing, axle-box and other assemblies that
are placed on the table of the handling dolly.
Herewith the electric drive motor load factor may
vary depending on the table load.
It is necessary to analyse the reduction of active
power losses in the motor and the electrical net-
work when replacing the under-loaded motor
mounted during the equipment manufacture with
the less powerful motor when washing other (non-
traction motors) units of the locomotive.
Initial data: electric drive mode is long-term.
AIR series motor with the following parameters
[4, 9]:
nom1
90 kWP
=
,
m nom
380 VU = ,
m nom1
0.93
η
= ,
nom1
cos 0.91
ϕ
= ,
nom1
160 AI
=
,
хх1
cos 0.15
ϕ
= . Motor type – 5АМ250М2.
The analysis is performed in accordance with
[13]. We propose the following method [6, 7, 14].
Losses of active power in no-load mode of
5АМ250М2 motor:
3
хх1 хх1m nom хх1
3 cos 10PIU
−
∆
=ϕ⋅=
3
3 48 380 0.15 10 4.73 kW
−
=⋅⋅ ⋅ ⋅ = (1)
No-load current:
хх1nom1
0.3 0.3 160 48 АII
=
=⋅ = , (2)
where 0.3 – coefficient according to [12].
Then the relative losses in no-load mode:
хх1
хх1
nom1
100%
P
P
P
∗
∆
∆
=⋅=
4.73
100% 5.25%
90
=⋅ =
(3)
The motor load factor:
1
nom
r
l
P
k
P
=
, (4)
where
r
P – actual load of the mounted motor of
the washing machine.
The feasibility of reducing the installed motor
power must be justified with calculations, if:
(
)( )
1
0.4...0.5 0.7...0.75
l
k≤< (5)
We accept:
1
0.7
l
k = . Then:
1nom1
0.7 90 63 kW
rl
PkP
=
=⋅= . The closest to
63 kW
r
P
=
and more powerful is the motor of
5AM250S4 type [3]. Specifications of 5АМ250S4
type motor:
nom2
75 kWP
=
,
m nom
380 VU = ,
m nom2
0.93
η
=
,
nom2
cos 0.91
ϕ
=
,
nom2
134.6 AI =
,
хх2
cos 0.15
ϕ
= .
55
ISSN 2307–3489 (Print), ІSSN 2307–6666 (Online)
Наука та прогрес транспорту. Вісник Дніпропетровського
національного університету залізничного транспорту, 2016, № 5 (65)
ЕЛЕКТРИЧНИЙ ТРАНСПОРТ
doi 10.15802/stp2016/83992 © L. V. Dubynets, O. L. Marenych, O. Yu. Baliichuk, A. S. Kortohus, 2016
Then for 5АМ250S4 type motor:
3
хх2 хх2m nom хх2
3cos10PIU
−
∆= ϕ⋅ =
3
3 40.38 380 0.15 10 3.98 kW
−
=⋅ ⋅ ⋅ ⋅ = (6)
No-load current:
хх2nom2
0.3 0.3 134.6 40.38 АII==⋅=, (7)
хх2
хх2
ном2
3.98
100% 100% 5.3%
75
P
P
P
∗
∆
∆=⋅=⋅= (8)
The total active power losses
1
P
∑
∆
for
5AM250M2 type motor:
(
)
()
22
1 хх1 1 1 nom e
1
ll
PQ k kQk
∑
∆= − + +
2
хх11in1
l
PkP+∆ + ∆ , (9)
where
3
хх1m nomхх1
310QUІ
−
=⋅ (10)
– reactive power consumed from the network in
no-load mode;
3
хх1
3 380 48 10 31.55 kVArQ
−
=⋅ ⋅⋅ = .
nom1
nom1 nom1
m nom1
tg
QP
⎛⎞
ϕ
=⋅
⎜⎟
η
⎝⎠
(11)
− reactive motor power in rated load mode;
nom1
0.456
90 44.13 kVAr
0.93
Q
⎛⎞
=⋅ =
⎜⎟
⎝⎠
(
)
nom1 nom1
tg tg arccosϕ= ϕ ,
where
nom1
cos ϕ – nominal motor power factor;
е
k
– increased loss coefficient or economic
equivalent, which determines the active power
losses for transmission of one kVAr of reactive
power into these power supply systems,
е
kW
0.125
kVAr
k = for low voltage consumers
[4];
in1
P∆ – increased active power losses in the
electric motor for 100% load;
m nom1
in1 nom1
m nom1 1
11
1
PP
−η
∆= ⋅
η+γ
, (12)
where
хх1
1
in1
P
P
∆
γ=
∆
– design coefficient depending
on the electric motor design and calculated by the
formula:
()
хх1
1
m nom1 хх1
100 1
P
P
∗
∗
∆
γ=
−η −∆
(13)
()
1
5.25
3
100 1 0.93 5.25
γ= =
−−
in1
10.93 1
90 1.7 kW
0.93 1 3
P
−
∆= ⋅ =
+
Then,
(
)
(
)
22
1
31.55 1 0.7 0.7 44.13 0.125P
∑
∆
=−+⋅⋅+
2
4.73 0.7 1.7 10.27 kWт++⋅=
Similarly, the total active power losses for less
powerful motor of 5АМ250S4type:
хх2m nomхх2
3QUІ
=
=
3
3 380 40.38 10 26.55 kVAr
−
=⋅ ⋅ ⋅ = (14)
nom2
nom2 nom2
m nom2
tg
QP
⎛⎞
ϕ
=
⋅=
⎜⎟
η
⎝⎠
0.456
75 36.77 kVAr
0.93
⎛⎞
=⋅ =
⎜⎟
⎝⎠
(15)
()
хх2
2
m nom2 хх2
100 1
P
P
∗
∗
∆
γ= =
−η −∆
()
5.3
1.7
100 1 0.93 5.3
==
−−
(16)
m nom2
in2 nom2
m nom2 2
1
1
1
PP
−η
∆
=⋅=
η
+γ
10.93 1
75 2.09 kW
0.93 1 1.7
−
=⋅=
+
(17)
(
)
(
)
22
2 хх222nome
1
ll
PQ k kQk
∑
∆
=−+ +
2
хх22in2
l
PkP+∆ + ∆ (18)
56
ISSN 2307–3489 (Print), ІSSN 2307–6666 (Online)
Наука та прогрес транспорту. Вісник Дніпропетровського
національного університету залізничного транспорту, 2016, № 5 (65)
ЕЛЕКТРИЧНИЙ ТРАНСПОРТ
doi 10.15802/stp2016/83992 © L. V. Dubynets, O. L. Marenych, O. Yu. Baliichuk, A. S. Kortohus, 2016
2
nom2
63
0.84
75
r
l
P
k
P
=== (19)
(
)
()
22
2
26.55 1 0.84 0.84 36.77 0.125P
∑
∆= − + ⋅ ⋅ +
2
3.98 0.84 2.09 9.69 kW++ ⋅ =
Thus, after replacing the under-loaded motor
5AM250M2 at
1
0.7
l
k = with the less powerful
motor 5AM250S4 in the washing machine, we ob-
tained the reduction of active power losses in the
motor and the electricity network:
12
10.27 9.69 0.58 kWPP P
∑∑
∆=∆ −∆ = − = (20)
Similarly, we conducted the calculations and
the analysis of active power loss reduction in the
motor and the electricity network, if
1
0.65; 0.6; 0.55; 0.5
l
k =
at 3000 r.p.m.;
n = 1500 r.p.m.; 1000 r.p.m.;
750 r.p.m.
When choosing [3] the motor type which is the
closest to the more powerful one relative to the real
load
r
P , it is necessary to provide:
2
nom2
0.9
r
l
P
k
P
=≤ (21)
We obtained the following results for the mo-
tors at 3000 r.p.m.
When
1
0.65
l
k = : 58.5 kW
r
P
=
. The closest
more powerful, than 58.5 kW
r
P = , is 5AM250S4
type motor (as when
1
0.7
l
k = ).
(
)
()
22
1
31.55 1 0.65 0.65 44.13 0.125P
∑
∆= − + ⋅ ⋅ +
2
4.73 0.65 1.7 10.07 kW++ ⋅=
2
0.78
l
k =
(
)
()
22
2
26.55 1 0.78 0.78 36.77 0.125P
∑
∆= − + ⋅ ⋅ +
2
3.98 0.78 2.09 8.69 kW++ ⋅ =
12
10.07 8.69 1.38 kWPP P
∑∑
∆=∆ −∆ = − =
When
1
0.6
l
k = : 54 kW
r
P = .
(
)
(
)
22
1
31.55 1 0.6 0.6 44.13 0.125P
∑
∆
=−+⋅⋅+
2
4.73 0.6 1.7 9.85 kW++⋅=
2
0.72
l
k
=
(
)
(
)
22
2
26.55 1 0.72 0.72 36.77 0.125P
∑
∆
=−+⋅⋅+
2
3.98 0.72 2.09 8.37 kW++ ⋅ =
12
9.85 8.37 1.48 kWPP P
∑∑
∆
=∆ −∆ = − =
When
1
0.55
l
k
=
: 49.5 kW
r
P
=
. The closest
more powerful motor is 5A225M2 type (55 kW,
3000 r.p.m. ). Here it is ensured
2
49.5
0.9
55
l
k ==.
(
)
(
)
22
1
31.55 1 0.55 0.55 44.13 0.125P
∑
∆
=−+⋅⋅+
2
4.73 0.55 1.7 9.67 kW++ ⋅=
хх2
nom2
0.25
I
I
= (according to [7] we take this ratio as
0.25, which is the average value of this ratio for the
power range 22.5 … 110 kW and corresponds to
the average power – 55 kW).
хх2
24.8 AI
=
;
хх2
2.45 kWP
∆
= ;
хх2
4.45 %P
∗
∆=
(
)
(
)
22
1
31.55 1 0.55 0.55 44.13P
∑
∆
=−+⋅×
2
0.125 4.73 0.55 1.7 9.67 kW×++⋅=
хх2
16.3 kVArQ
=
;
nom2
27.11 kVArQ
=
;
2
1, 4 6γ=
in 2
1.83 kWP
∆
= .
(
)
(
)
22
2
16.3 1 0.9 0.9 27.11P
∑
∆
=−+⋅×
2
0.125 2.45 0.9 1.83 7.06 kW×++⋅=
12
9.67 7.06 2.61 kWPP P
∑∑
∆=∆ −∆ = − = .
When
1
0.5
l
k
=
:
45 kW
r
P
=
. The closest more
powerful motor is 5А225М2 type.
2
0.82
l
k = .
(
)
(
)
22
1
31.55 1 0.5 0.5 44.13P
∑
∆
=−+⋅×
2
0.125 4.73 0.5 1.7 9.495 kW×++⋅=
57
ISSN 2307–3489 (Print), ІSSN 2307–6666 (Online)
Наука та прогрес транспорту. Вісник Дніпропетровського
національного університету залізничного транспорту, 2016, № 5 (65)
ЕЛЕКТРИЧНИЙ ТРАНСПОРТ
doi 10.15802/stp2016/83992 © L. V. Dubynets, O. L. Marenych, O. Yu. Baliichuk, A. S. Kortohus, 2016
(
)
()
22
2
16.3 1 0.82 0.82 27.11P
∑
∆= − + ⋅ ×
2
0.125 2.45 0.82 1.83 6.63 kW×++⋅=
12
9.495 6.63 2.865 kWPP P
∑∑
∆=∆ −∆ = − =
.
Similarly, the following values of P∆ are ob-
tained for AIR series motors at 1500 r.p.m.
For AIR series motors at 1000 r.p.m. we ob-
tained the following.
For AIR series motors at 750 r.p.m. we ob-
tained the following.
For illustration purposes we will show
(
)
1l
Pfk∆= in the form of Table 1.
The parameters listed in Table 1 are obtained
for the types of electric motors shown in Table 2.
When
1
0.7
l
k = :
1
10.59P
∑
∆= kW
2
9.23P
∑
∆
= kW
1.36P∆= kW
When
1
0.65
l
k = :
1
10.48P
∑
∆= kW
2
9.09P
∑
∆
= kW
1.39P∆=
kW
When
1
0.6
l
k =
:
1
10.34P
∑
∆=
kW
2
8.92P
∑
∆=
kW
1.42P∆= kW
When
1
0.55
l
k = :
1
10.25P
∑
∆= kW
2
7.415P
∑
∆
= kW
2.835P∆= kW
When
1
0.5
l
k = :
1
10.128P
∑
∆= kW
2
7.17P
∑
∆
= kW
2.96P∆=
kW
When
1
0.7
l
k =
:
1
11.43P
∑
∆=
kW
2
9.73P
∑
∆=
kW
1.7P∆= kW
When
1
0.65
l
k = :
1
11.37P
∑
∆= kW
2
9.64P
∑
∆
= kW
1.73P∆= kW
When
1
0.6
l
k = :
1
11.3P
∑
∆= kW
2
9.55P
∑
∆
= kW
1.75P∆= kW
When
1
0.55
l
k =
:
1
11.23P
∑
∆=
kW
2
8.49P
∑
∆=
kW
2.74P∆= kW
When
1
0.5
l
k = :
1
11.17P
∑
∆= kW
2
8.37P
∑
∆
= kW
2.8P∆= kW
When
1
0.7
l
k = :
1
13.04P
∑
∆= kW
2
10.9P
∑
∆
= kW
2.14P∆= kW
When
1
0.65
l
k =
:
1
13.02P
∑
∆=
kW
2
10.825P
∑
∆=
kW
2.195P∆= kW
When
1
0.6
l
k = :
1
12.98P
∑
∆= kW
2
9.16P
∑
∆
= kW
3.82P∆= kW
When
1
0.55
l
k = :
1
12.86P
∑
∆= kW
2
7.84P
∑
∆
= kW
5.02P∆= kW
When
1
0.5
l
k =
:
1
12.87P
∑
∆=
kW
2
7.73P
∑
∆=
kW
5.09P∆= kW
58