Designing an Uninterruptible Power Supply

Guide for electrical design engineers
Julian Wiatr
PowerQuality
Power Quality
Example of a process production line
Designing an uninterruptible power supply

2
http://www.leonardo-energy.org
Power Quality
Scope of design
A company specialized in uninterruptible power supply systems developed and manufactured in 2006 a system
comprising a 400kVA UPS unit. The system was installed in a production facility manufacturing food packaging
equipment and foil, located in northern Poland. Frequent voltage dips and fluctuations were severely impairing the
production process, causing downtimes of several-hour duration, which generated substantial losses. Restarting the
production caused another losses resulting from the process specificity. Typically about 200 kg of material was lost
until final product was compliant with standards.
The production plant is supplied directly from two-transformer substation 15/0.42 kV. The substation is not equipped
with automatic stand-by switching system and is provided only with a manually operated power switch 1—0—2
(In
=1250A). According to the design of electrical installation in the production line room, individual loads were
supplied directly from LV switchboard in the transformer substation; a fire cut-off switch was not installed.
Since the commissioning of the uninterruptible power supply system the process line has been operating failure
free. Supply interruptions, even of a several minute duration, do not cause the process breakdown. The transformer
substation was provided with fire cut-off switch actuated by manually operated switches located at the main entrance
to the production room and at the entrance to the UPS room. Actuation of the fire switch turns the UPS off and thus
turns off all loads installed in the building. Photographs below show some elements of the uninterruptible power
supply installation.
View of the uninterruptible power supply installation
Air-conditioning
The design of the uninterruptible power supply system installation involved some problems related with efficiently
venting of hydrogen released during the UPS battery charging. The room intended by the investor for the UPS
installation was very small what resulted in the necessity for design of ventilation and air conditioning installation.
Charging of lead-acid batteries involves hydrogen evolution due to water decomposition (even in a sealed battery
there is no 100% recombination). This process is associated with the water decomposition voltage of ca. 0.23 V. Water
decomposition process in lead-acid battery is indicated in figure 1.

3
equilibrium voltage
~ 2 V
0,23 V
water
decomposition
voltage
hydrogengassing
hydrogenevolution
oxygenevolution
-0,8 -0,6 -0,4 -0,2 0 1,4 1,6 1,8 2,0 2,2 [v]
2H+
+2e−
→H2
02-
→ ½-02-
+2e
Fig. 1. Water decomposition in a lead-acid battery
Fig. 2. The ignition energy of a hydrogen-air mixture vs. the hydrogen concentration
Z1
– minimum ignition energy Emin
=0,019 mJ,
Vd
– lower explosive limit
Vg
– upper explosive limit
Accumulating hydrogen gas mixes with air forming a mixture that at the concentration greater than 4.1% (lower
explosive limit — LEL) becomes explosive. When the concentration exceeds the lower explosive limit even a small
energy, e.g. that of an electrostatic discharge, is sufficient to initiate explosion. The floor in the battery room shall be
of an antistatic material that enables an electrostatic charge accumulated on human body flow to earth. The floor
resistance shall satisfy the condition: 50 kΩ ≤ R ≤ 1*10Ω. Fulfilling this condition provides for both: a proper workplace
insulation, according to IEC 60364-4-41 requirements, and sufficient flow of static charge to earth. The dependence
of ignition energy of a hydrogen-air mixture on the hydrogen concentration is shown in figure 2.
Hydrogen has a lighter density than air and tends to rise upward in air, forming under a ceiling a layer of mixture with
concentration depending on the intensity of battery gassing and the air exchange rate in the battery room. In order
to mitigate explosion hazards the UPS battery room ventilation is necessary.
The presented design employs a two-threshold explosive gases detection system. The detection system comprises
a control panel, two detectors and an optical-audible signaling device. If the concentration exceeds 10% of the lower
explosive limit (LEL) an exhaust fan with air exchange rate 6 times per hour is started. If the gassing is more intensive

4
Power Quality
and the concentration exceeds 30% of LEL, the second exhaust fan is started. Both fans provide for air exchange rate
12 times per hour (the required rate is 4–8 air exchanges per hour).
When the concentration exceeds 30% of LEL the acoustic-optical signaling device is actuated which warns the staff to
turn-on the ventilation with the manually operated switch located outside the UPS room.
Approximate air demand volume per hour in [m3
/h] can be calculated from the formula [1]:
Qp
= 0.05 * n * Ig * CB
where: Ig
– gassing current value:
1 mA – for sealed batteries at variable voltage
5 mA – or vented batteries at variable voltage
8 mA – for sealed batteries at constant charging voltage
20 mA – for vented batteries at constant charging voltage
n – number of cells
CB
– battery capacity.
It should be borne in mind that forced ventilation shall always be provided. A gravity (natural) ventilation may
be applied if the ventilation openings fulfilling the following condition can be provided:
Ap
= 28 * Qp
where: Ap
– total cross sectional area of the intake and outlet openings [cm2
].
In such case the ventilation openings shall be placed on the opposite walls.Where this is impracticable and ventilation
openings have to be made in same wall, the distance between openings must not be smaller than 2 m. The same
requirement applies to installation of exhaust fans whose distance must not be smaller than 2 m. These requirements
shall be used solely for informative purposes. Design of battery room ventilation requires specialist knowledge and
should only be made by a certified designer. The role of an electrical engineer is confined to the design of control and
power supply systems for ventilating fans.
The design employs air conditioners in order to remove the surplus heat dissipated by equipment installed in the UPS
room. The use of air conditioners also allows maintaining air humidity required by the UPS unit. Appropriate relative
humidity air is an important factor for the generation of static charges and thus reduction of electrostatic discharge
hazard. Specification for ventilators and air conditioners is provided by the HVAC part of design.
Specification and design calculations
The process equipment power supply switchboard is supplied from a two-transformer substation with two 800 kVA
transformers. The substation is provided with a manual stand-by switching system. The process equipment power
supply and control panel is fed directly from the two-transformer 15/0.42 kV substation main switchboard through
a feeder cable 5x(3xYKY 1x150) {5x(3xH1VV1X150)}. The load current does not exceed 180 A in each phase of the
feeder line.
Technical specification of the substation transformers:
- Rated power Sn
= 800 kVA
- Connection group Dy5,

5
- Nominal voltage of primary side Un1
= 15000 V
- Nominal voltage of secondary side Un2
= 420 V
- Short-circuit voltage uk
= 0.060
- Nominal load losses ΔPobc zn
= 8.5 kW.
Short-circuit capacity at the point of transformers connection to MV line: SkQ
= 250 MVA.
Air conditioner rating: P = 8 kW; kr
= 4; Un
= 3x230/400 V; cosϕ = 0.9; η=0.9.
Ventilator rating: P = 1.0 kW; kr
= 4;Un
=3x230/400 V; cosϕ = 0.9; η=0.9.
Technical description of installation
Since the second production line is planned to be installed, the process equipment power supply and control panel
shall be supplied from UPS 400 kVA (a single production line could be supplied from a 200 kVA UPS that sufficiently
fulfills the supply requirements).
Schematic diagram of the process equipment power supply is shown in drawing 3, diagram of the ventilation control
circuits is shown in drawing 3A; diagram of the MD-2A control panel connections is shown in drawing 3B.
The separated part of production room shall be adapted to the UPS purposes. Equipment layout in the UPS room
is shown in drawing 5.The layout of ventilation and air-conditioning installation in the UPS room is shown in drawing 6.
Diagrams of switchboards installed in the UPS room are shown in drawings 7, 7A, 7B, 8, 8A and 8B. Schematic diagram
of the compressor and water treatment plant power supply switchboard is shown in drawings 9, 10A, 10B and 10C.
Drawing 4 shows the layout of the uninterruptible power supply circuit.
The UPS room shall also be provided with two air conditioners; their selection and location is within the scope
of mechanical and HVAC part of design.
The UPS room shall be separated from the rest of production room with a wire mesh fence not less than 3 m high.
The fence design is outside the scope of this study. The UPS room is an electrical room therefore warning signs shall
be placed on the fencing and access of unauthorized persons shall be prevented.
At the main entrance to the production room a fire cut-off switch shall be installed. Above the switch a sign shall be
placed with information on its purpose and use.
Selection of the UPS unit
The peak load current under the process line normal operating conditions, measured in each phase is: I1
=I2
=I3
= I = 180 A.
The process line shall be supplied with compressed air and process water in order to ensure continuity of its
operation.
The peak power of additional equipment (of capacity sufficient for two process lines) is:
- compressor with a soft start system – Psp
= 11 kW,
- water treatment plant – PSUW
= 41 kW.
Calculated active power demand at the UPS output
P U I kW kW
P P P P P
n
c wyjUPS SUW sp
1
1
3 3 400 180 124 71 125
2
= ⋅ ⋅ = ⋅ ⋅ = ≈
= = ⋅ + +
.
== ⋅ + + =
=
≥ = =
2 125 41 11 302
0 8
302
0 8
37
kW
S
P
z
wyjUPS
wyjUPS
z
cos .
cos .
ϕ
ϕ
77 5. kVA

6
Power Quality
Therefore the 400 kVA unit shall be selected
where: SwyjUPS
– reactive peak power at the UPS output [kVA]
Pc
– active peak power at the UPS output [kW]
P1
– active peak power of process line equipment (installation of second process line is planned as
a target solution) [kW]
I – load current of the process line equipment under normal operating conditions and peak load
(determined from measurement) [A]
cosφz
– power factor of the process line equipment (calculated from the equipment manufacturer O&M
instructions) [-]
Un
– nominal voltage of loads [V]
PwyjUPS
– UPS output active power [kW]
PSUW
– active peak power of water treatment [kW]
Psp
– compressor active peak power [kW].
Cable sizing for continuous current-carrying capacity and thermal effects of overload current:
— UPS calculated power demand:
S
P
W
P
W
wejUPS
wyjUPS wyjUPS
UPS
=
⋅
+
⋅⎛
⎝
⎜
⎞
⎠
⎟
= ⋅
+η
ϕ
0 25 302
0 9 0 9
0.
cos
. .
..
.
.
~ .
25 302
0 9
0 9
507 50
⋅
≈ kVA
— UPS feeder cables and external bypass (protection: overcurrent power circuit breaker 800 A):
I
S
U
A
I A I A I
I
B
wejUPS
n
B n Z
Z
=
⋅
=
⋅
=
= ≤ = ≤
≥
3
507500
3 400
732 50
732 50 800
,
,
kk I
An2
1 45
1 45 800
1 45
800
⋅
=
⋅
=
.
,
.
where: Swej UPS
– UPS apparent peak power [kVA]
W – UPS input current distortion factor determined from the manufacturer O&M instruction
η – UPS efficiency determined from the manufacturer O&M instruction [-]
cosφUPS
– UPS power factor determined from the manufacturer O&M instruction [-]
IB
– load current [A]
In
– nominal current of protective device [A]
IZ
– required continuous current-carrying capacity of a cable [A]
k2
– multiple factor of a protective device rated current at which the protective device operates at
the specified conventional time, equal [7]:
1.6- 2.1 – for fuse links
1.45 – for overcurrent circuit breakers
1.2 – for overcurrent selective circuit breakers and bimetallic relays

7
The selected cable 4x(2xYKXS 1x240) + YKXSżo 240 {4x(2xH1V4V1X240) + H1V4V1G240} satisfies the requirements of
IEC 60364-45-523 standard regarding continuous current-carrying capacity and thermal effects of overload current:
Iz
’
= kp
* Iz
= 0.85 ∗ 2 ∗ 538 = 914.60 A > 800 A.
Note: The main protection of RUPS feeder, installed in the transformer substation LV switchboard supplying the production room, is only a short-
circuit protection. Since no overloads are expected the RUPS supply circuit the existing cable 5x(3xYKXS 1x150) {5x(3xH1VV1X150)} can be
considered adequate for power supply of RUPS.
- RS and UW feeder cable (protection: fuse 125 A):
I
P
U
A
I A
B
RS i UW
n RS i UW
B
=
⋅ ⋅
=
⋅ ⋅
=
=
_ _
_ _cos ,
.
.
3
52000
3 400 0 8
93 82
93 82
ϕ
≤≤ = ≤
≥
⋅
=
⋅
=
I A I
I
k I
A
n Z
Z
n
125
1 45
1 6 125
1 45
137 932
.
,
.
.
The selected cable YKXSżo 5x50 {5xH1V4V5G50} satisfies the requirements of IEC 60364-45-523 standard regarding
continuous current-carrying capacity and thermal effects of overload current:
Iz
’
= kp
* Iz
= 0.8 * 179 = 143.20 A > 137.93 A.
- Compressor feeder cable (protection: fuse 40 A):
I
P
U
A
I A I A I
B
SP
n SP
B n Z
=
⋅ ⋅
=
⋅ ⋅
=
= ≤ = ≤
3
11000
3 400 0 8
19 85
19 84 40
cos ,
.
.
ϕ
II
k I
AZ
n
≥
⋅
=
⋅
=2
1 45
1 6 40
1 45
44 14
.
,
.
.
The selected cable YKXSżo 5x6 {H1V4V5G6} satisfies the requirements of IEC 60364-45-523 standard regarding
Iz
’
= kp
* Iz
= 0.8 * 52 = 41.60 A > 44.14 A.
- Water treatment plant feeder cable (protection: fuse 80 A):
I
P
U
A
I A I A
B
SUW
n SUW
B n
=
⋅ ⋅
=
⋅ ⋅
=
= ≤ = ≤
3
41000
3 400 0 8
73 97
73 97 80
cos ,
.
.
ϕ
II
I
k I
A
Z
Z
n
≥
⋅
=
⋅
=2
1 45
1 6 80
1 45
88 28
.
,
.
.
The selected cable YKXSżo 5x16 {H1V4V5G16} satisfies the requirements of IEC 60364-45-523 standard regarding
Iz
’
= kp
* Iz
= 1 * 96 A = 96 A > 88.28 A

8
Power Quality
- Ventilation fan feeder cable (protection: S303C4):
I
P
U
A A
I A
B
W
n SUW
B
=
⋅ ⋅ ⋅
=
⋅ ⋅ ⋅
≈ =
=
3
1000
3 400 0 9 0 9
1 782 1 79
1 79
cos , .
. .
.
ϕ η
≤≤ = ≤
≥
⋅
=
⋅
=
I A I
I
k I
A
n Z
Z
n
4
1 45
1 45 4
1 45
42
.
,
.
In addition: Ir
= kr * IB
= 4 * 1.79 = 7.16 < k4 * In
= 5 * 4 = 20 A, therefore the selection of protection shall be considered
appropriate with respect to starting currents.
The selected installation cable YDYżo 4x1.5 {H1VV4G1.5} satisfies the requirement of IEC 60364-45-523 standard
regarding continuous current-carrying capacity and thermal effects of overload current:
Iz
’
= kp
* Iz
= 1 * 17.5 A=17.5 A > 4 A
- Air conditioner feeder cable (protection: S303C16):
I
P
U
A
I A I
B
W
n SUW
B n
=
⋅ ⋅ ⋅
=
⋅ ⋅ ⋅
≈
= ≤ =
3
8000
3 400 0 9 0 9
14 26
14 26 1
cos , .
.
.
ϕ η
66
1 45
1 45 16
1 45
162
A I
I
k I
A
Z
Z
n
≤
≥
⋅
=
⋅
=
.
,
.
In addition: Ir
= kr * IB
= 4 * 14.26 = 71.30 < k4 * In
= 5 * 16 = 80 A, therefore the selection of protection shall be considered
appropriate with respect to starting currents.
The selected installation cable YDYżo 4 x 1.5 [H1VV4G1.5] satisfies the requirement of IEC 60364-45-523 standard
regarding continuous current-carrying capacity and thermal effects of overload current:
Iz
’
= kp
* Iz
= 1 * 24 A=24 A > 14.26 A
where: Psp
– compressor active power [kW]
PSUW
– water treatment plant active power [kW]
cosφsp
– compressor power factor determined from the manufacturer technical specification
cosφSUW
– water treatment plant power factor determined from the manufacturer technical specification
k4
– multiple factor of the rated current of the overload release lower operation limit
of a miniature overcurrent electromagnetic circuit breaker [-].
Cable size checking for short-circuit conditions:
- Power system impedance as seen from the point of transformer connection to the MV network reflected to the
transformer low-voltage side:
Z
C U
S
U
UkQ
n
kQ
n
n
=
⋅
⋅
( )
=
⋅
⋅
⋅
⎛
⎝
⎜
⎞
⎠
max .1 2
2
1
2
6
1 10 15000
250 10
420
15000
⎟⎟ =
= ⋅ = ⋅ =
=
2
0 000776
0 995 0 995 0 000776 0 000772
0 1
.
. , . .
.
Ω
ΩX Z
R
kQ kQ
kQ ⋅⋅ = ⋅ =XkQ 0 1 0 000772 0 000772, . . Ω

9
where: ZkQ
– short-circuit impedance of the power system [Ω]
XkQ
– short-circuit reactance of the power system [Ω]
RkQ
– short-circuit resistance of the power system [Ω]
SkQ
– short-circuit capacity at the point of transformer connection to the power system,
as determined by the utility company [MVA]
Un1
– nominal voltage of the transformer high-voltage side [V]
Un2
– nominal voltage of the transformer low-voltage side [V].
- Impedance of the transformer:
Z u
U
S
I
U
Z
kT k
n
T
k
n
kT
= ⋅ = ⋅ =
′′ =
⋅
=
⋅
2
2
2
3
2
0 06
0 42
0 8
0 0132
3
400
3 0 0
.
,
.
.
.
Ω
11323
17 50
2 2 1 4 17 50 34 65
≈
= ⋅ ⋅ ′′= ⋅ ⋅ ≈
.
. . .
kA
i I kAp kκ
According to the catalogue specification the resistance and reactance of the 15/0.42 kV 800kVA transformer is,
respectively:
RT
= 0.0023 Ω - resistance of the supply transformer
XT
= 0.0130 Ω - reactance of the supply transformer
R R R
X X X
k kQ T
k kQ T
= + = + = ≈
= + =
0 0000772 0 0023 0 0023772 0 0024
0 0
. . . .
.
Ω Ω
000772 0 0130 0 013772 0 0133
0 0024 0 01332 2 2 2
+ = ≈
= + = + =
. . .
. .
Ω Ω
Z R Xk k k 00 0135
0 0024
0 0133
0 18
0 0133
0 0024
2 3 14 5
.
.
.
.
.
.
.
Ω
R
X
T
X
R
k
k
k
k
= ≈
= =
⋅ ⋅ω 00
0 0177 17 7≈ =. .s ms
′′ =
⋅
=
⋅
≈I
U
Z
kAk
n
kT
3
2
3
400
3 0 0135
17 11
.
.
κ = + ⋅ = + ⋅ =
−
− ⋅
1 02 0 98 1 02 0 98 1 59
3
3 0 18
. . . . .,
e e
R
X
k
k
Z u
U
S
i I
kT k
n
T
p k
= ⋅ = ⋅ =
= ⋅ ⋅ ′′= ⋅ ⋅
2
2 2
0 06
0 42
0 8
0 0132
2 2 1 59 17 1
.
.
.
.
. .
Ω
κ 11 38 72≈ . kA
- Required minimum cross sectional area of the feeder cable:
RUPS protection: overcurrent power circuit breaker 1250 A with operating time setting:
Tk
= 0.5 s (Tk
= 0.5s > 10∗T = 0.18s) – thus the simplified relationship Ith
≈ I”k
can be used for calculation:
S
k
I T
mm mmk k
≥
′′
=
⋅
= <<
1
1
1
135
17500 0 5
1
91 67 450
2 2
2 2.
,

10
Power Quality
Other UPS circuits protection: overcurrent power circuit breaker 800 A with operating time set
Tk
= 0.4 s – Ics
=40 kA s (Tk
=0.5 s > 10∗T = 0.18 s) – thus the simplified relationship Ith
≈ I”k
can be used for calculation:
S
k
I T
mm mmk k
≥
′′
=
⋅
= <<
1
1
1
135
17500 0 4
1
82 480
2 2
2 2.
- The process equipment power supply and control panel protection:
400 A fuse – Ics
= 100 kA:
S
k
I t
mm mmw
≥ = = <<
1
1
1
135
1600000
1
9 37 480
2
2 2
.
- RS and UW feeder protection: 125 A fuse – Ics
=100kA:
S
k
I t
mm mmw
≥ = = <<
1
1
1
135
104000
1
2 39 50
2
2 2
.
- Air conditioners power supply (protection: S303C16 –Ics
= 6 kA)
S
k
I t
mm mmw
≥ = = <
1
1
1
115
8000
1
0 78 4
2
2 2
.
- Ventilation fans power supply (protection: S303C4 –Ics
= 6 kA)
S
k
I t
mm mmw
≥ = = <
1
1
1
115
5000
1
0 62 1 5
2
2 2
. .
where:
I2
tw
– fuse link operation Joule integral [A2
∗s]
k – one-second short-circuit current permissible density [A/mm2
]
Ics
– rated service short-circuit capacity [kA]
S – required minimum cross sectional area of a conductor [mm2
]
I”k
– initial short-circuit current [kA]
T – time constant of short-circuit loop [s]
ω – angular frequency
Ith
– thermal equivalent short-circuit current [kA].
Checking the RS and UW feeder cable for permissible voltage drop:
Note: Due to the distance of RS and UW to the power source, only the feeder line is to be checked for voltage drop. Distances of other circuit
elements to the power source are negligible thus they could be disregard in design calculations; calculation of these voltage drops is left
to the interested reader.
ΔU
P L
S Un
≥
⋅ ⋅
⋅ ⋅
=
⋅ ⋅
⋅ ⋅
= <
100 52000 60 100
55 50 400
0 71 1 02 2
%
. % . %
γ
The condition is satisfied.

11
Required cross sectional area of protective conductors PE with regard to the effectiveness of electric shock
protection in the case the installation is supplied from UPS:
- RS and UW:
R
U
IPE
L
a
≤ = =
50
1475
0 033. Ω
S
L
R
mm mmPE
PE
PE
_min
.
.≥
⋅
=
⋅
= <
γ
60
0 033 55
33 06 502 2
The selected cable satisfies the conditions for protection against electric shock.
- The process equipment power supply and control panel:
R
U
IPE
L
a
≤ = =
50
5280
0 0094. Ω
S
L
R
mm mmPE
PE
PE
_min
.
.≥
⋅
=
⋅
= <<
γ
50
0 0094 55
29 02 2402 2
- Other elements of the uninterruptible powers supply system
R
U
IPE
L
a
≤ = =
50
6400
0 0078. Ω
S
L
R
mm mmPE
PE
PE
_min
.
≥
⋅
=
⋅
= <<
γ
15
0 0078 55
35 2402 2
where: SPE_min
– required minimum cross sectional area of the protective conductor [mm2
]
LPE
– length of the protective conductor [m]
RPE
– maximum resistance of the protective conductor [Ω]
Ia
– operating current of the protective device [A], within the time required by IEC 60364-4-41
standard, determined from the current-time characteristic provided by a manufacturer (here:
for T=0.4s)
γ – conductivity of the conductor [m/(Ω⋅mm2
)].

12
Checking the automatic disconnection of supply in the case the installation is not supplied from the UPS system:
- RUPS switchboard
According to the catalogue specification the resistance and reactance of the 15/0.42 kV 800kVA transformer is,
respectively:
RT
= 0.0023 Ω – resistance of the supply transformer
XT
= 0.0130 Ω – reactance of the supply transformer
Resistance of the RUPS feeder line:
R
L
SL1
20
55 450
0 00081=
⋅
=
⋅
=
γ
. Ω
Reactance of RUPS feeder line:
X
x L
L1
3
0 08 0 02
3
0 00053=
⋅( )
=
⋅( )
=
’ . .
. Ω
The impedance of short-circuit loop:
Z R R R X X Xk kQ T L kQ T L1 1
2
12 2
0 0000772 0 0023 2 0 00
= + + ⋅( ) + + + ⋅( )=
+ + ⋅. . . 0081 0 000772 0 0130 2 0 000530 0 01462 2
( ) + + + ⋅( )=. . . . Ω
Line-to-earth fault current at RUPS
i
U
Z
A I Ak
k
alT sk1
0
1
0 5
0 8 0 8 230
0 0146
12603 10000=
⋅
=
⋅
= >> ==
. .
. ,
where: L – length of the feeder line [km]
RL
– resistance of the feeder line [Ω]
XL
– reactance of the feeder line [Ω]
U0
– voltage between the phase conductor and earthed protective conductor PE [V]
Zk1
– impedance of the short-circuit loop for line-to-earth fault [Ω]
Ia
– operating current of the protective device within the time required by IEC 60364-4-41 standard,
determined from the characteristic t =f(Ik
), provided by the protective device a manufacturer [A]
x’ – reactance per unit length of cable (assumed 0.08 Ω/km)
γ – conductivity of the conductor [m/(Ω⋅mm2
)].
Power Quality

13
Other calculation results are listed in Table 1.
No. Item Zk
[Ω] Ik1
[A] Protection Ia
[A]
Condition
Ik1
≥Ia
1 UPS unit 0.015 12266.66 NS800N 5600/Tk
=0.4 s +
2 External Bypass 0.015 12266.66 NS800N 5600/Tk
=0.4s +
3 Air conditioner I 0.110 1672.72 S303C16 160/Tk
=0.1s +
4 Air conditioner II 0.130 1415.38 S303C16 160/ Tk
=0.1s +
5 Fan I 0.260 707.69 S303C4 40/ Tk
=0.1s +
6 Fan II 0.360 511.11 S303C4 40/ Tk
=0.1s +
7 RS and UW 0.060 3006.66 WTN00gG125 1475/ Tk
=0.4s +
8 Process RG 0.020 9200.00 WTN2gG400 5280/ Tk
=0.4s +
9 CSW 0.130 1415.38 S301C2 20/ Tk
=0.1s +
10 Water treatment plant 0.080 2300.00 WTN00gG80 776/ Tk
=0.4s +
11 Compressor 0.075 2453.33 WTN00gG40 300/ Tk
=0.4s +
Table 1. The effectiveness of automatic disconnection of supply for other elements
of the uninterruptible power supply system — calculation results
Therefore the designed installation provides effective protection against electric shock.
Note: In these calculations the reactance of conductors with cross sectional area SCu
≤ 50 mm2
or SAl
≤ 70 mm2
can be neglected.
Concluding remarks
1. The part of the production room adapted for the UPS purposes shall be separated and signed with warning
safety signs; an access of unauthorized persons shall be prevented.
2. Installation and assembly of the UPS unit shall be exclusively made by the manufacturer service or an
authorized person.
3. All accessible conductive parts shall be bonded to the main earthing bar. The bonding shall be made with
installation cable LgYżo 35 {H1V-K1G35}.
4. The UPS room floor shall be covered with insulating mats.
5. Upon completion of installation works all necessary tests and measurements shall be carried out according
to the requirements of IEC 60364-6-61 standard and the manufacturer’s specification.
6. The selected UPS unit meets the power demand of the planned second process line. The installation of the
uninterruptible power supply system is designed to meet these requirements.
7. Operators shall receive an adequate training prior to the system commissioning.
8. Before the second process line commissioning the MV/LV 2 x 800 kVA transformer substation should be
provided with automatic stand-by switching with electrical and mechanical interlocks.
9. Cables in the battery circuits are sized according to the UPS manufacturer’s specification.

14
Specification of basic materials
1. UPS unit 1 set
2. Battery banks (90 Ah) 3 sets
3. Battery rack 3 pcs
4. Battery disconnector 1250 A, wall mounted enclosure 3 sets
5. External bypass 1 pc
6. Pushbutton operated emergency-stop switch 1 pc
7. Switchboard RUPS acc. to dwg. 7; 7A; 7B 1 pc
8. Switchboard RNG acc. to dwg. 8; 8A; 8B 1 pc
9. Switchboard RS and UW acc. to dwg. 10; 10A; 10B 1 pc
10. Cable YKY 1 x 240 {H1VV1X240} 180 m
11. Cable YKYżo 5 x 50 {H1VV5G50} 60 m
14. Installation cable LgYżo 25 {H1V-K1G35} 50 m
15. Cable trays 30 m
16. Installation cable NKGx 2x2.5 or equivalent 40 m
17. Control panel 1 pc
18. Optical-audible signaling device 1 pc
19. Hydrogen concentration detectors 2 pcs
20. Power supply 17 Ah 1 pc
21. Other installation fitting, accessories, materials as required.
Note: Items 1—6 are covered by the order placed at the UPS supplier.
Since the transformer substation is supplied via two independent overhead lines outgoing from the same main
feeding point (MFP), an engine generating set (EGS) shall be installed in order to improve the reliability of supply. Its
rated power shall be sufficient to cover the peak power of all equipment installed in the production room. In addition
a manually operated power switch 1—0—2 shall be replaced with an automatic stand-by switching system as an
explicit redundancy.
References:
1. M. Miegoń, A. Przasnyski; J. Wiatr - Systemy zasilania gwarantowanego Powerware. Poradnik projektanta
i wykonawcy. [Uninterruptible power supply systems Powerware. Designer’s and contractor’s guide] (in
Polish) – the EATON QUALITY Company Poland 2006.
2. IEC 60364 Standard: Electrical installations of buildings.
3. EATON POWERWARE products catalogue.
4. www.elektro.info.pl
Power Quality

15
Existing transformer
substation TR 15/0,42 kV
2x800 kVA
Note:
US - Ventilation control system, type MD-2 manufactured by "GAZEX".
CSW - Ventilation control panel
D - Explosive gas detector manufactured by "GAZEX"
Transformer substation is not equipped with automatic stand-by switching system. It supplies
only the loads installed in the production room. The production building has no cable joint;
feeding cables are brought directly into switchboards installed in the production room.
Cable type designation used by
Polish manufacturers
Cable type designation compliant
with PN-HD 361
Battery disconnector
Batteries 1
Batteries 2
Batteries 3
Main battery
disconnector
air cond.I air cond.II
Dwg. 3. Schematic diagram of the uninterruptible power supply system

16
k2
L1L2L3N
F8
S301C2
PS3-17Ah the gas
detection system
control panel power
supply
Two-threshold gas detection
system MD-2 - Dwg. 6
12 V
PE
A1
A2
YDY2x1,5
2
YDYzo 3x2,5
2
k1
L1L2L3N
F7
S301C2
PE
A1
A2
M M
S303C4S303C4
W - manual control
2
3x230/400 V - RUPS - see Dwg. 4
YDY2x1,5
01
F6
S301C2
with PN-HD 361
Dwg. 3A. Schematic diagram of the ventilation system control
Power Quality

17
comNONC
A2
comNONC
A1
Contactoutputs
12Vfrom
powersupply
PS3-17Ah
YDYzo3x2.5fromRUPS
Powersupplyfrom230V
networkDwg.4
Powersupply
PS3-17Ah
comNONC
Failure
MDX+
M+
A2
M+
A1
12Voutput
-A1A2
Alarm
input12V
M12+
1
M12+
2
DETEKTOR1
DEX-71C
MD-2A
DETEKTOR1
DEX-71C
YDY2x1.5toA1andA2k3inRUPS(On
exceeding30%DGWcontactsareclosingandk2
isenergized-seeDrg.3A)
Optical-audible
signalingdevice
SL-21
YDY3x1,5
YDY2x1.5toA1andA2k3inRUPS
(Onexceeding10%DGWcontactsare
closingandk1isenergized-seeDrg.3A)
YDY4x1YDY4x1
Cabletypedesignationusedby
Polishmanufacturers
Cabletypedesignationcompliant
withPN-HD361
Dwg. 3B. Connection diagram of the hydrogen detection panel

18
UPSroom-acc.todrawing3
WatertreatmentplantCompressor
Processequipmentsupplyandcontrol
panel.Existing
Existingcableduct
UPSunit
Firecut-offswitch
Stafffacilities-according
tothestructuraldesign
Productionprocessroom
Emergencystopswitch
Processroom−accordingtothestructuraldesign
Polishmanufacturers
withPN-HD361
Dwg. 4: Layout of uninterruptible power supply cable lines
Power Quality

19
BatteryrackST
(SBL-12i)
ProcessLine1powersupplyswitchboard-Existing
TheUPSroomwiremeshfencingacc.tothe"KRAM"
companydesign;h=3m
Note:
Cabletypesaredesignatedindrawing4.
Powerratingsofventilatorsandairconditionersareas
givenintheventilationdesignpart.
NKGx2x2.5tofirecut-offswitch
atthebuildingmainentrance
Batterydisconnector
Batterydisconnector
Batterydisconnector
Tothemonitordisplaypanelinthe
ProductionManager'sroom
VentilationcontrolpanelMD-2+powersupplyPS3
Polishmanufacturers
withPN-HD361
BatteryrackST
(SBL-12i)
BatteryrackST
(SBL-12i)
Mainbattery
disconnector
Dwg. 5: UPS installation layout

20
Process Line 1 power supply switchboard - Existing
Ventilation control panel MD-2 + power supply PS3
Note:
W - Exhaust ventilators, rated power 1.0 kW each. Air conditioners shall be
installed 30 cm below the ceiling level.
D - explosive gas detectors of GAZEX manufacture, installed on the
ceiling.
Ventilation
manual switch
Optical-audible signaling device SL-21
Dwg. 6: Layout of ventilation and air conditioning installation
Power Quality

21
with PN-HD 361
Dwg. 9. Schematic diagram of RS and UW

22
Dwg. 7: View of RUPS cabinet without covers
Power Quality

23
Dwg. 7A: View of RUPS cabinet with covers

24
Dwg. 7B: View of RUPS cabinet with doors
Power Quality

25
Dwg. 8: View of RNG cabinet without covers

26
Dwg. 8A: View of RNG cabinet with covers
Power Quality

27
Dwg. 8B: View of RNG cabinet with doors

28
Dwg. 10: Assembly diagram of RS and UW
Power Quality

29
Dwg. 10A: View of RS and UW with covers

30
This publication is subject to copyright and a disclaimer. Please refer to the Leonardo ENERGY website.
Power Quality

Designing an Uninterruptible Power Supply

More Related Content

What's hot (20)

Similar to Designing an Uninterruptible Power Supply (20)

More from Leonardo ENERGY (20)

Recently uploaded (20)

Designing an Uninterruptible Power Supply