The Surge Protection Device (SPD): Difference between revisions

Latest revision as of 08:45, 26 January 2021

Surge Protection Devices (SPD) are used for electric power supply networks^[1], telephone networks, and communication and automatic control buses.

The Surge Protection Device (SPD) is a component of the electrical installation protection system.

This device is connected in parallel on the power supply circuit of the loads that it has to protect (see Fig. J17). It can also be used at all levels of the power supply network.

This is the most commonly used and most efficient type of overvoltage protection.

Fig. J17 – Principle of protection system in parallel

SPD connected in parallel has a high impedance. Once the transient overvoltage appears in the system, the impedance of the device decreases so surge current is driven through the SPD, bypassing the sensitive equipment.

Principle

SPD is designed to limit transient overvoltages of atmospheric origin and divert current waves to earth, so as to limit the amplitude of this overvoltage to a value that is not hazardous for the electrical installation and electric switchgear and controlgear.

SPD eliminates overvoltages

in common mode, between phase and neutral or earth;
in differential mode, between phase and neutral.

In the event of an overvoltage exceeding the operating threshold, the SPD

conducts the energy to earth, in common mode;
distributes the energy to the other live conductors, in differential mode.

The three types of SPD

Type 1 SPD

The Type 1 SPD is recommended in the specific case of service-sector and industrial buildings, protected by a lightning protection system or a meshed cage.

It protects electrical installations against direct lightning strokes. It can discharge the back-current from lightning spreading from the earth conductor to the network conductors.

Type 1 SPD is characterized by a 10/350 µs current wave.

Type 2 SPD

The Type 2 SPD is the main protection system for all low voltage electrical installations. Installed in each electrical switchboard, it prevents the spread of overvoltages in the electrical installations and protects the loads.

Type 2 SPD is characterized by an 8/20 µs current wave.

Type 3 SPD

These SPDs have a low discharge capacity. They must therefore mandatorily be installed as a supplement to Type 2 SPD and in the vicinity of sensitive loads.

Type 3 SPD is characterized by a combination of voltage waves (1.2/50 μs) and current waves (8/20 μs).

SPD normative definition

Fig. J18 – SPD standard definition

	Direct lightning stroke	Indirect lightning stroke
IEC 61643-1	Class I test	Class II test	Class III test
IEC 61643-11/2011	Type 1 :	Type 2 :	Type 3 :
EN/IEC 61643-11	Type 1	Type 2	Type 3
Former VDE 0675v	B	C	D
Type of test wave	10/350	8/20	1.2/50 + 8/20

Note 1: There exist + SPD (or Type 1 + 2 SPD) combining protection of loads against direct and indirect lightning strokes.
Note 2: some SPD can also be declared as .

Characteristics of SPD

International standard IEC 61643-11 Edition 1.0 (03/2011) defines the characteristics and tests for SPD connected to low voltage distribution systems (see Fig. J19).

In green, the guaranteed operating range of the SPD.

Fig. J19 – Time/current characteristic of a SPD with varistor

Common characteristics

Uc: Maximum continuous operating voltage

This is the A.C. or D.C. voltage above which the SPD becomes active. This value is chosen according to the rated voltage and the system earthing arrangement.

Up: Voltage protection level (at In)

This is the maximum voltage across the terminals of the SPD when it is active. This voltage is reached when the current flowing in the SPD is equal to In. The voltage protection level chosen must be below the overvoltage withstand capability of the loads. In the event of lightning strokes, the voltage across the terminals of the SPD generally remains less than Up.

In: Nominal discharge current

This is the peak value of a current of 8/20 µs waveform that the SPD is capable of discharging minimum 19 times^[2].

Why is I_n important?
I_n corresponds to a nominal discharge current that a SPD can withstand at least 19 times^[2]: a higher value of I_n means a longer life for the SPD, so it is strongly recommended to chose higher values than the minimum imposed value of 5 kA.

Type 1 SPD

I_imp: Impulse current

This is the peak value of a current of 10/350 µs waveform that the SPD is capable of discharging of discharging at least one time^[3].

Why is I_imp important?
IEC 62305 standard requires a maximum impulse current value of 25 kA per pole for three-phase system. This means that for a 3P+N network the SPD should be able to withstand a total maximum impulse current of 100kA coming from the earth bonding.

I_fi: Autoextinguish follow current

Applicable only to the spark gap technology. This is the current (50 Hz) that the SPD is capable of interrupting by itself after flashover. This current must always be greater than the prospective short-circuit current at the point of installation.

Type 2 SPD

I_max: Maximum discharge current

This is the peak value of a current of 8/20 µs waveform that the SPD is capable of discharging once.

Why is I_max important?
If you compare 2 SPDs with the same I_n, but with different I_max: the SPD with higher Imax value has a higher "safety margin" and can withstand higher surge current without being damaged.

Type 3 SPD

Uoc: Open-circuit voltage applied during class III (Type 3) tests.

Main applications

Low Voltage SPD

Very different devices, from both a technological and usage viewpoint, are designated by this term. Low voltage SPDs are modular to be easily installed inside LV switchboards.

There are also SPDs adaptable to power sockets, but these devices have a low discharge capacity.

SPD for communication networks

These devices protect telephone networks, switched networks and automatic control networks (bus) against overvoltages coming from outside (lightning) and those internal to the power supply network (polluting equipment, switchgear operation, etc.).

Such SPDs are also installed in RJ11, RJ45, ... connectors or integrated into loads.

Notes

^ find out more in application examples such as SPD for EV charging application, SPD for photovoltaic applications and SPD application example in Supermarket
^ ¹ ²
Test sequence according to standard IEC 61643-11 for SPD based on MOV (varistor). A total of 19 impulses at In:
- One positive impulse
- One negative impulse
- 15 impulses synchronised at every 30°on the 50 Hz voltage
- One positive impulse
- One negative impulse
^
for type 1 SPD, after the 15 impulses at In (see previous note):
- One impulse at 0.1 x Imp
- One impulse at 0.25 x Imp
- One impulse at 0.5 x Imp
- One impulse at 0.75 x Imp
- One impulse at Imp

[Ref1-1] ut more in application examples such as SPD for EV charging application, SPD for photovoltaic applications and SPD application example in Supermarket

[Ref2-2] ¹ ² Test sequence according to standard IEC 61643-11 for SPD based on MOV (varistor). A total of 19 impulses at In:
One positive impulse

One negative impulse

15 impulses synchronised at every 30°on the 50 Hz voltage

One positive impulse

One negative impulse

[3] One positive impulse

[4] One negative impulse

[5] 15 impulses synchronised at every 30°on the 50 Hz voltage

[6] One positive impulse

[7] One negative impulse

[Ref3-3] r type 1 SPD, after the 15 impulses at In (see previous note):
One impulse at 0.1 x Imp

One impulse at 0.25 x Imp

One impulse at 0.5 x Imp

One impulse at 0.75 x Imp

One impulse at Imp

[9] One impulse at 0.1 x Imp

[10] One impulse at 0.25 x Imp

[11] One impulse at 0.5 x Imp

[12] One impulse at 0.75 x Imp

[13] One impulse at Imp

[1]

[2]

[3]

@@ Line 1: / Line 1: @@
-{{Menu_Overvoltage_protection}}
+{{Menu_Overvoltage_protection}}__TOC__
-__TOC__
 {{Highlightbox|
-Surge Protection Devices (SPD) are used for electric power supply networks, telephone networks, and communication and automatic control buses.
+Surge Protection Devices (SPD) are used for electric power supply networks{{fn|1}}, telephone networks, and communication and automatic control buses.}}
-}}
-The Surge Protection Device (SPD) is a component of the electrical installation protection system.<br>This device is connected in parallel on the power supply circuit of the loads that it has to protect (see '''Fig. J17'''). It can also be used at all levels of the power supply network. <br>This is the most commonly used and most efficient type of overvoltage protection.
+The Surge Protection Device (SPD) is a component of the electrical installation protection system.
+This device is connected in parallel on the power supply circuit of the loads that it has to protect (see {{FigRef|J17}}). It can also be used at all levels of the power supply network.
-[[File:Fig J17 EN.jpg|none]]
+This is the most commonly used and most efficient type of overvoltage protection.
-'''''Fig. J17:''' Principle of protection system in parallel''
+{{FigImage|DB422477_EN|svg|J17|Principle of protection system in parallel}}
+{{Highlightbox|
+SPD connected in parallel has a high impedance. Once the transient overvoltage appears in the system, the impedance of the device decreases so surge current is driven through the SPD, bypassing the sensitive equipment.}}
-'''Principle'''<br>SPD is designed to limit transient overvoltages of atmospheric origin and divert current waves to earth, so as to limit the amplitude of this overvoltage to a value that is not hazardous for the electrical installation and electric switchgear and controlgear.
+==Principle==
-'''SPD eliminates overvoltages:'''
+SPD is designed to limit transient overvoltages of atmospheric origin and divert current waves to earth, so as to limit the amplitude of this overvoltage to a value that is not hazardous for the electrical installation and electric switchgear and controlgear.
+'''SPD eliminates overvoltages'''
 *in common mode, between phase and neutral or earth;
 *in differential mode, between phase and neutral.
 In the event of an overvoltage exceeding the operating threshold, the SPD
 *conducts the energy to earth, in common mode;
 *distributes the energy to the other live conductors, in differential mode.
-'''The three types of SPD:'''
+'''The three types of SPD'''
-*'''Type 1 SPD'''
+'''Type 1 SPD'''
-The Type 1 SPD is recommended in the specific case of service-sector and industrial buildings, protected by a lightning protection system or a meshed cage.<br>It protects electrical installations against direct lightning strokes. It can discharge the back-current from lightning spreading from the earth conductor to the network conductors.<br>Type 1 SPD is characterized by a 10/350 µs current wave.
+The Type 1 SPD is recommended in the specific case of service-sector and industrial buildings, protected by a lightning protection system or a meshed cage.
-*'''Type 2 SPD'''
+It protects electrical installations against direct lightning strokes. It can discharge the back-current from lightning spreading from the earth conductor to the network conductors.
-The Type 2 SPD is the main protection system for all low voltage electrical installations. Installed in each electrical switchboard, it prevents the spread of overvoltages in the electrical installations and protects the loads. <br>Type 2 SPD is characterized by an 8/20 µs current wave.
+Type 1 SPD is characterized by a 10/350 µs current wave.
-*'''Type 3 SPD'''
+'''Type 2 SPD'''
-These SPDs have a low discharge capacity. They must therefore mandatorily be installed as a supplement to Type 2 SPD and in the vicinity of sensitive loads.Type 3 SPD is characterized by a combination of voltage waves (1.2/50 μs) and current waves (8/20 μs).
+The Type 2 SPD is the main protection system for all low voltage electrical installations. Installed in each electrical switchboard, it prevents the spread of overvoltages in the electrical installations and protects the loads.
-*'''SPD normative definition'''
+Type 2 SPD is characterized by an 8/20 µs current wave.
-{| class="wikitable" style="width: 743px; height: 54px" width="743"
+'''Type 3 SPD'''
+These SPDs have a low discharge capacity. They must therefore mandatorily be installed as a supplement to Type 2 SPD and in the vicinity of sensitive loads.
+Type 3 SPD is characterized by a combination of voltage waves (1.2/50 μs) and current waves (8/20 μs).
+'''SPD normative definition'''
+{{tb-start|id=Tab1292|num=J18|title=SPD standard definition|cols=5}}
+{| class="wikitable"
 |-
-! &nbsp;
+!
 ! Direct lightning stroke
 ! colspan="2" | Indirect lightning stroke
@@ Line 54: / Line 61: @@
 | Class III test
 |-
-| '''IEC 61643-11/2007'''
+| '''IEC 61643-11/2011'''
-| Type 1&nbsp;: [[File:Fig J T1.jpg|26x26px]]
+| Type 1 : [[File:Symbol-T1.gif]]
-| Type 2&nbsp;:&nbsp; [[File:Fig J T2.jpg|26x26px]]
+| Type 2 : [[File:Symbol-T2.gif]]
-| Type 3&nbsp;:&nbsp; [[File:Fig J T3.jpg|28x30px]]
+| Type 3 : [[File:Symbol-T3.gif]]
 |-
 | '''EN/IEC 61643-11'''
@@ Line 69: / Line 76: @@
 | D
 |-
-| Type of test wave
+| '''Type of test wave '''
 | 10/350
 | 8/20
 | 1.2/50 + 8/20
 |}
+{{tb-notes
-Note 1: There exist [[File:Fig J T1.jpg|26x26px]] &nbsp; + &nbsp;[[File:Fig J T2.jpg|26x26px]] SPD (or Type 1 + 2 SPD) combining protection of loads against direct and indirect lightning strokes.<br>Note 2: some [[File:Fig J T2.jpg|26x26px]] SPD can also be declared as [[File:Fig J T3.jpg|28x30px]].
+|txn1= '''Note 1''': There exist [[File:Symbol-T1.gif]]  + [[File:Symbol-T2.gif]]  SPD (or Type 1 + 2 SPD) combining protection of loads against direct and indirect lightning strokes.
+|txn2= '''Note 2''': some [[File:Symbol-T2.gif]] SPD can also be declared as [[File:Symbol-T3.gif]].}}
-'''''Fig. J18:''' SPD standard definition''
 == Characteristics of SPD  ==
-International standard IEC 61643-1 Edition 2.0 (03/2005) defines the characteristics and tests for SPD connected to low voltage distribution systems (see '''Fig. J19''').
+International standard IEC 61643-11 Edition 1.0 (03/2011) defines the characteristics and tests for SPD connected to low voltage distribution systems (see {{FigRef|J19}}).
-[[File:Fig J19.jpg|none]]
+{{FigImage|DB422478|svg|J19|Time/current characteristic of a SPD with varistor|In green, the guaranteed operating range of the SPD.}}
-&nbsp;&nbsp;&nbsp; In green, the guaranteed<br>
+===Common characteristics===
-&nbsp;&nbsp;&nbsp; operating range of the SPD.
-'''''Fig. J19:''' Time/current characteristic of a SPD with varistor''
+*'''Uc''': Maximum continuous operating voltage
+:This is the A.C. or D.C. voltage above which the SPD becomes active. This value is chosen according to the rated voltage and the system earthing arrangement.
+*'''Up''': Voltage protection level (at In)
+:This is the maximum voltage across the terminals of the SPD when it is active. This voltage is reached when the current flowing in the SPD is equal to In. The voltage protection level chosen must be below the overvoltage withstand capability of the loads. In the event of lightning strokes, the voltage across the terminals of the SPD generally remains less than Up.
+*'''In''': Nominal discharge current
+:This is the peak value of a current of 8/20 µs waveform that the SPD is capable of discharging minimum 19 times{{fn|2}}.
+{{Highlightbox|'''Why is I<sub>n</sub> important?'''<br>
+I<sub>n</sub> corresponds to a nominal discharge current that a SPD can withstand at least 19 times{{fn|2}}: a higher value of I<sub>n</sub> means a longer life for the SPD, so it is strongly recommended to chose higher values than the minimum imposed value of 5 kA.}}
-*'''Common characteristics'''
+===Type 1 SPD===
-&nbsp; - Uc: Maximum continuous operating voltage<br>This is the A.C. or D.C. voltage above which the SPD becomes active. This value is chosen according to the rated voltage and the system earthing arrangement.<br>&nbsp; - Up: Voltage protection level (at In)<br>This is the maximum voltage across the terminals of the SPD when it is active. This voltage is reached when the current flowing in the SPD is equal to In. The voltage protection level chosen must be below the overvoltage withstand capability of the loads. In the event of lightning strokes, the voltage across the terminals of the SPD generally remains less than Up. <br>&nbsp; - In: Nominal discharge current <br>This is the peak value of a current of 8/20 µs waveform that the SPD is capable of discharging 15 times.
+*'''I<sub>imp</sub>''': Impulse current
+:This is the peak value of a current of 10/350 µs waveform that the SPD is capable of discharging of discharging at least one time{{fn|3}}.
-*'''Type 1 SPD'''
+{{Highlightbox|'''Why is I<sub>imp</sub> important?'''<br>
+IEC 62305 standard requires a maximum impulse current value of 25 kA per pole for three-phase system. This means that for a 3P+N network the SPD should be able to withstand a total maximum impulse current of 100kA coming from the earth bonding.}}
-&nbsp; - Iimp: Impulse current<br>This is the peak value of a current of 10/350 µs waveform that the SPD is capable of discharging 5 times.<br>&nbsp; - Ifi: Autoextinguish follow current <br>Applicable only to the spark gap technology.<br>This is the current (50 Hz) that the SPD is capable of interrupting by itself after flashover. This current must always be greater than the prospective short-circuit current at the point of installation.
+*'''I<sub>fi</sub>''': Autoextinguish follow current
+:Applicable only to the spark gap technology. This is the current (50 Hz) that the SPD is capable of interrupting by itself after flashover. This current must always be greater than the prospective short-circuit current at the point of installation.
-*'''Type 2 SPD'''
+===Type 2 SPD===
-&nbsp; - Imax: Maximum discharge current<br>This is the peak value of a current of 8/20 µs waveform that the SPD is capable of discharging once.
+*'''I<sub>max</sub>''': Maximum discharge current
+:This is the peak value of a current of 8/20 µs waveform that the SPD is capable of discharging once.
-*'''Type 3 SPD'''
+{{Highlightbox|'''Why is I<sub>max</sub> important?'''<br>
+If you compare 2 SPDs with the same I<sub>n</sub>, but with different I<sub>max</sub>: the SPD with higher Imax value has a higher "safety margin" and can withstand higher surge current without being damaged.}}
-&nbsp; - Uoc: Open-circuit voltage applied during class III (Type 3) tests.
+===Type 3 SPD===
+*'''Uoc''': Open-circuit voltage applied during class III (Type 3) tests.
 == Main applications  ==
 *Low Voltage SPD
+: Very different devices, from both a technological and usage viewpoint, are designated by this term. Low voltage SPDs are modular to be easily installed inside LV switchboards.
-Very different devices, from both a technological and usage viewpoint, are designated by this term. Low voltage SPDs are modular to be easily installed inside LV switchboards. <br>There are also SPDs adaptable to power sockets, but these devices have a low discharge capacity.
+: There are also SPDs adaptable to power sockets, but these devices have a low discharge capacity.
 *SPD for communication networks
+: These devices protect telephone networks, switched networks and automatic control networks (bus) against overvoltages coming from outside (lightning) and those internal to the power supply network (polluting equipment, switchgear operation, etc.).
+: Such SPDs are also installed in RJ11, RJ45, ... connectors or integrated into loads.
-These devices protect telephon networks, switched networks and automatic control networks (bus) against overvoltages coming from outside (lightning) and those internal to the power supply network (polluting equipment, switchgear operation, etc.).<br>Such SPDs are also installed in RJ11, RJ45, ... connectors or integrated into loads.
+{{footnotes}}
+<references>
-[[zh:浪涌保护器 （SPD）]]
+{{fn-detail|1|find out more in application examples such as [[EV charging - electrical installation design#Protection against transient overvoltages|SPD for EV charging application]], [[SPD for photovoltaic applications]] and [[SPD application example in Supermarket]]}}
+{{fn-detail|2|Test sequence according to standard IEC 61643-11 for SPD based on MOV (varistor). A total of 19 impulses at In:
+* One positive impulse
+* One negative impulse
+* 15 impulses synchronised at every 30°on the 50 Hz voltage
+* One positive impulse
+* One negative impulse}}
+{{fn-detail|3|for type 1 SPD, after the 15 impulses at In (see previous note):
+* One impulse at 0.1 x Imp
+* One impulse at 0.25 x Imp
+* One impulse at 0.5 x Imp
+* One impulse at 0.75 x Imp
+* One impulse at Imp}}
+</references>