PRELIMINARY
69
P
ROTECTIONS INSIDE THE
UPS
The following table shows the sizes of the disconnecting switches on the UPS system as well as the sizes of the battery fuses
(SWBATT); these devices can be accessed from the front of the UPS.
The table also provides details on the internal fuses (not accessible) used to protect the input and output lines, and the
maximum input and nominal output currents. Please refer to the block diagrams in the “USAGE” section of the “Description
paragraph for the position of the fuses.
Fuses must be replaced with fuses of the same rating and with the same characteristics as indicated in the table.
Disconnecting switches and Internal protections
UPS
Model
Non automatic switches
Battery fuse
Current
[kVA]
UPS Input
UPS Output/
Maintenance/Separate
Bypass
Input current
[A] Max
*
Output
current
[A]
3P+N **
SWIN
SWOUT / SWMB /
SWBYP (optional)
SWBATT
L1***
L2/L3
P+N
Nominal
10
63A(4P)
63A(2P)
32A gG 400V (10x38)
49A
18A
55A
45A
12
63A(4P)
63A(2P)
32A gG 400V (10x38)
59A
21A
64A
55A
15
100A(4P)
100A(2P)
50A gG 400V (14x51)
72A
25A
76A
68A
20
100A(4P)
100A(2P)
50A gG 400V (14x51)
95A
33A
98A
91A
*
The maximum input current refers to a nominal load (PF = 0,8) and to an input voltage of 346V (200V for single-phase
connections), and with the battery charger under charge at 4A.
**
On versions with additional internal battery chargers (optional), the maximum input current on lines L2 and L3 should be
increased to 7A.
***
When operating off the bypass with a three-phase connection, all the output current is applied to L1 and Neutral.
SHORT-CIRCUIT
In the event of a fault on the load, in order to protect itself the UPS limits the value and the duration of the power supplied (short
circuit current). These values also depend on the operating status of the unit at the time of the fault, which is either:
§
UPS in NORMAL MODE: the load is instantly switched over to the bypass line (I
2
t=25000A
2
s): the input line is
connected to the output without any internal protection and shuts down after t>0.5s
§
UPS in BATTERY MODE: the UPS protects itself by supplying output current of around 1.5 times the nominal current
for 0.5s and then shuts down.
BACKFEED
The UPS is also protected internally against backfeed through metal separation devices.
An optional relay output card is available to ensure the control of a release device to be installed upstream of the UPS.
The UPS has an internal device (redundant bypass power supply) which in the event of a fault automatically
activates the bypass while ensuring power to the load without any internal protection and without any limit on the
power supplied to the load.
In these emergency conditions, any disturbance on the input line will have repercussions on the charge.
Please also refer to the “Usage” section of the paragraph entitled “Redundant auxiliary power supply for automatic
bypass”.
PRELIMINARY
70
E
XTERNAL PROTECTION DEVICES
MAGNETOTHERMAL SWITCH
As outlined above, the UPS has devices to protect against faults on the output and internal faults.
To set up the power line install a
magneto-thermal switch
upstream of the UPS with intervention curve C in
compliance with the EN 60947 specification, following the indications given in the following table:
Automatic external protections
Mains input
UPS Model
Single-phase input (P+N)
Three-phase input (3P+N)
Separate bypass input (P+N)
Standard Ups
10 – 12 – 15 – 20 kVA
100A
100A
N.D.
Ups with separate bypass
15 – 20 kVA
100A
63A
100A
Ups with separate bypass
10 – 12 kVA
63A
40A
100A
If the protection device upstream of the UPS interrupts the neutral conductor, at the same time it must also interrupt
all the phase conductors (quadri-polar switch).
Output protection (recommended selectivity values)
Normal fuses (GI)
In (Nominal current)/7
Normal switches (C Curve)
In (Nominal current)/7
Ultra rapid fuses (GF)
In (Nominal current)/2
DIFFERENTIAL
In the standard version, the neutral from the mains power is connected to the UPS output neutral and the neutral settings of the
installation remain unchanged.
THE INPUT NEUTRAL IS CONNECTED TO THE OUTPUT NEUTRAL
THE DISTRIBUTION SYSTEM THAT POWERS THE UPS IS NOT CHANGED BY THE UPS
The neutral settings are changed only if an isolation transformer is installed or when the UPS operates with a
differential switch located upstream.
Make sure that the input neutral is connected correctly, because errors could damage the UPS
When operating from mains power, a differential switch located at the input intervenes so that the output circuit is not isolated
from the input circuit.
Extra differential switches can always be inserted at the output, and where possible, co-ordinated with the differential switches
at the input.
The differential switch upstream of the UPS must have the following features:
§
Differential current adjusted to the UPS load value; an adequate margin should be kept to avoid delayed interventions
(recommended value: 100mA min. - 300mA)
§
type B or type A
§
delay greater than or equal to 0.1s