Coordination of
Surge protection devices
Design guide
Surge arresters for commercial
and industrial buildings
Surge protective device
coordination
Protection
Load protection
Coordination between the surge protective device and
its disconnect circuit breaker
MCCB / MCB
I
Disconnector
coordinated with
surge protective
device
An external disconnecting device must be coordinated with a surge protective device
in order to achieve:
bb continuity of service:
vv do not trip due to surge current,
vv do not increase (Up) voltage protection level.
bb effective protection against all types of overcurrents:
vv overload due to SPD aging,
vv short circuit of low intensity (impedant) due to temporary overvoltages,
vv short circuit of high intensity due to SPD degradation.
MCB
L
SPD
L
Circuit
breaker
closed
Nonconducting
SPD
MCCB = Molded-case circuit breaker.
MCB = Modular circuit breaker.
SPD = Surge protective device.
L
Circuit
breaker
closed
Loads
Surge protective device in
normal operation
Conducting
SPD
Circuit
breaker
open
Loads
Surge protective device
in operation during the
lightning stroke
Conducting
SPD
Loads
Surge protective
device at end of life on
short circuit
The disconnecting device must be coordinated with the surge protective device. It is
designed to meet the following two constraints:
Resistance to lightning current
The resistance to lightning current is an essential characteristic of the surge
protective device's external disconnecting device.
The device must be capable of passing the following standardized tests: not trip
upon 15 successive impulse currents at In.
Resistance to short-circuit current
The breaking capacity is determined by the installation rules (IEC 60364
standard):
bb the external disconnecting device must have a breaking capacity equal to or
greater than the presumed short-circuit current Isc at the point of installation.
bb when this device is integrated into the surge protective device, conformity with
product standard IEC 61643-11 naturally ensures protection.
2
Version : 1.0
26/05/2015
CA903014E
Protection
Load protection
Surge protective device
coordination (cont.)
External disconnecting Fuse protection combined
device
with the SPD
Circuit breaker protection
combined with the SPD
Circuit breaker protection
integrated into the SPD
Lightning protection of
equipment
=
=
=
All types of disconnecting devices protect the equipment satisfactorily
Protection of installation
=
+
++
(at end of the surge protective Achieved if compliance with the MCB/SPD coordination table
Achieved during product design
device's life)
Protection from (impedant) short circuits Protection against (impedant) short circuits of low intensity
of low intensity not well ensured
Continuity of service
+
+
+
(at end of the surge protective Only the surge protective device circuit is shut down
device's life)
Maintenance (at end of the
=
+
+
surge protective device's life) Change of fuses
Immediate resetting
Main reasons why the disconnecting device recommended by the manufacturer
should be used:
bb if the disconnecting device's rating is lower than the recommended rating:
risk of the disconnecting device opening in normal operation.
bb if the disconnecting device's rating is higher than the recommended rating:
risk of non-disconnection during a temporary voltage surge.
CA903014E
Version : 1.0
26/05/2015
3
Surge protective device
coordination (cont.)
Protection
Load protection
Coordination between the surge protective device and its
disconnect circuit breaker in the event of a short circuit
This table shows: the rating, curve and short circuit current level of the disconnector coordinated with the surge
protective device.
Isc (kA)
50
NG125L
C63 A
NG125L
C63 A
NG125L
C63 A
NG125L
C80 A /
Compact
NSX 100N
100 A
Compact
NSX 100N
100 A
Compact
NSX 160N
160 A
NG125H
C63 A
NG125H
C63 A
NG125H
C63 A
NG125H
C80 A /
Compact
NSX 100F
100 A
Compact
NSX 100F
100 A
Compact
NSX 160F
160 A
iC60L
C10 A
iC60L
C20 A
NG125N
C40 A
NG125N
C50 A
NG125N
C80 A /
Compact
NSX 100B
100 A
iC60H
C10 A
iC60H
C20 A
iC60H
C50 A
iC60H
C50 A
C120H
C80 A /
Compact
NSX 100B
100 A
Compact
NSX 100B
100 A
Compact
NSX 160B
160 A
36
Disconnector
25
15
10
6
iC60N
C40 A
iC60N
C20 A
iC60N
C10 A
iQuick
PF 10
iPRD 8r
*
*
*
iQuick
PRD 40r
iQuick
PRD 20r
iQuick
PRD 8r
*
iK60N
C20 A
iPF K 20 iPRD 20r
iK60N
C40 A
iC60N
C50 A
iK60N
C50 A
Compact
NSX 100B
100 A
C120N
C80 A /
Compact
NSX 100B
100 A
*
iPF K 40 iPRD 40r iPF K 65 iPRD 65r iPRF1 12.5r PRD1 25r PRD1 Master PRF1 Master
Surge protective device
8 kA
10 kA
20 kA
40 kA
65 kA
12.5 kA
25 kA
35 kA
Imax / Iimp
2.5 kA
5 kA
5 kA
15 kA
20 kA
25 kA
25 kA
50 kA
In
Type 3(1)
(1) Uoc: 10 kV.
Type 2
Low risk
Medium risk
Type 1
High risk
Maximum risk
*
( ) For lightning impulse current withstand
4
Version : 1.0
26/05/2015
CA903014E
Surge protective device
coordination (cont.)
Protection
Load protection
Coordination between the surge protective device and
its disconnect fuse in the event of a short circuit
Isc (kA)
50
Fupact
125 A gG
max.
36
Fupact
125 A gG
max.
Fupact
125 A gG
max.
Disconnector
25
Fupact
63 A gG
15
Fupact
80 A gG
SBI +
25 A gG
(14x51 mm)
10
STI +
25 A gG
(10x38 mm)
SBI +
63 A gG
(22x58 mm)
STI +
32 A gG
(14x51 mm)
Fupact
160 A gG
SBI +
80 A gG
(22x58 mm)
Fupact
315 A gG
Fupact
250 A gG
Fupact
315 A gG
SBI +
50 A aM
(14x51 mm)
6
iPRD 8r
iPF K 20
iPRD 20r
iPF K 40
iPRD 40r
iPF K 65
iPRD 65r
iPRF1 12.5r
PRD1 25r
PRD1 Master PRF1 Master
Surge protective device
8 kA
20 kA
40 kA
65 kA
12.5 kA
25 kA
35 kA
Imax / Iimp
2.5 kA
5 kA
15 kA
20 kA
25 kA
25 kA
50 kA
In
Type 3(1)
(1) Uoc: 10 kV.
CA903014E
Type 2
Low risk
Medium risk
Version : 1.0
Type 1
High risk
Maximum risk
26/05/2015
5
Protection
Load protection
Surge protective device
coordination (cont.)
Coordination between two surge protective devices,
upstream/downstream
When two surge protective devices are installed
in an electrical installation, coordination is
needed according to IEC 61643-12 to obtain an
acceptable stress distribution between the two
surge protective devices according to their
permissible energy "E".
L
Zd
I1
IF
I2
MCB
Up1
L and Zd
Up2:
Uw:
Imax:
IF :
E:
MCB:
SPD:
SPD 1
MCB
Up2
SPD 2
represent the cable length and impedance respectively between the 2 surge protective devices.
level of protection of surge protective device SPD2.
impulse withstand voltage of the equipment to be protected.
maximum discharge current.
lightning current:
y Imax of SPD1
= I1 + I2
permissible energy.
modular circuit breaker.
surge protective device.
For coordination between two surge protective devices,
a minimum cable length between these 2 surge protective devices
is needed to ensure that:
@@I2 < Imax SPD2.
@@Up2 < Uw.
@@E2 < E max SPD2.
6
Version : 1.0
26/05/2015
CA903014E
Surge protective device
coordination (cont.)
Protection
Load protection
Minimum distance between two surge protective devices, upstream/downstream
For a cable section of 16 mm2 and an impulse current equal to the maximum discharge current (Imax) of the
upstream surge protective device.
Example
If iPRD65r is installed in the incoming panelboard, the second SPD iPRD8r must be installed at a cable
length of 8 meters from the first one.
Type 2
Type 1
Upstream surge protective device
iQuick
PRD 20r
iQuick
PRD 40r
iPRD 20r
iPRD 65r
iPRF1 12.5r PRD1 25r
PRD1 Master
0m
10 m
10 m
10 m
0m
2m
10 m
10 m
10 m
3m
2m
10 m
10 m
0m
2m
10 m
10 m
iPRD 40r
iPRD 65r
0m
Type 3
Downstream surge protective device
Type 2
iPRD 40r
iPRD 20r
0m
iQuick
PRD 40r
2m
0m
0m
iQuick
PRD 20r
0m
1m
0m
2m
2m
10 m
10 m
iPRD 8r
3m
7m
4m
9m
8m
10 m
10 m
iQuick
PRD 8r
2m
6m
4m
7m
7m
10 m
10 m
CA903014E
Version : 1.0
26/05/2015
10 m
7
Protection
Load protection
Surge protective device
coordination (cont.)
Cascading in the event of a short circuit between the
surge protective device disconnector and the upstream
circuit breaker
What is cascading?
Cascading means using the circuit breakers' limiting power, which
allows circuit breakers of lower performance to be installed
downstream.
The upstream circuit breakers then act as a barrier for major
short-circuit currents. They thus enable circuit breakers of
breaking capacity lower than the presumed short-circuit current (at
their point of installation) to be loaded in their normal breaking
conditions.
Since current limiting takes place all along the circuit controlled by
the upstream current-limiting circuit breaker, cascading concerns
all the devices located downstream of that circuit breaker.
It is not restricted to two consecutive devices.
Case 1
Disconnect circuit breaker not integrated into
the surge protective device.
For this type of study, refer to the existing coordination tables.
see 557F4200 catalogue module.
MCCB / MCB
MCB
SPD
MCCB = Molded-case circuit breaker.
MCB = Modular circuit breaker.
SPD = Surge protective device.
8
Version : 1.0
26/05/2015
CA903014E
Protection
Load protection
Surge protective device
coordination (cont.)
Case 2
Disconnect circuit breaker
integrated into the surge
protective device.
Isc (kA)
50
NG125L C25 A
NG125L C63 A
NG125L C63 A
iQuick
PRD 8r
iQuick
PRD 20r
iQuick
PRD 40r
NG125H C25 A
NG125H C63 A
NG125H C63 A
iQuick
PRD 8r
iQuick
PRD 20r
iQuick
PRD 40r
36
MCCB / MCB
SPD
25
MCCB = Molded-case circuit breaker.
MCB = Modular circuit breaker.
SPD = Surge protective device.
15
NG125H C20 A
iQuick PF 10
10
iQuick
PRD 8r
iQuick
PRD 20r
iQuick
PRD 40r
20 kA
40 kA
5 kA
15 kA
iC60N C20 A
iQuick PF 10
6
iQuick PF 10
Imax
In
8 kA
2.5 kA
Type 3
(1)
(1) Uoc: 10 kV.
CA903014E
10 kA
5 kA
Version : 1.0
Type 2
Low risk
26/05/2015
Medium risk
9
© 2015 - Schneider Electric - All rights reserved.
Schneider Electric Industries SAS
35, rue Joseph Monier
CS 30323
F- 92506 Rueil Malmaison Cedex
As standards, specifications and designs change from time to time, please ask for confirmation of
the information given in this publication.
Printed on ecological paper
www.schneider-electric.com
Publication: Schneider Electric
Photos: Schneider Electric
Printing:
CA903014E
05-2015
Surge protective device
coordination (cont.)
s
n
o
i
t
u
l
Evo
in
g
Protection
Load protection
T
h
lis
ub
p
e
his
or
page
d bef
must be remove
1.0
Indice
12/05/2015
Date
CA903014E
Creation
Sonovision
Modification
Name
Version : 1.0
26/05/2015
11