The components of a SPD: Difference between revisions
From Electrical Installation Guide
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The SPD chiefly consists of (see | The SPD chiefly consists of (see {{FigRef|J48}}):<br>1) one or more nonlinear components: the live part (varistor, gas discharge tube, etc.);<br>2) a thermal protective device (internal disconnector) which protects it from thermal runaway at end of life (SPD with varistor);<br>3) an indicator which indicates end of life of the SPD;<br>Some SPDs allow remote reporting of this indication;<br>4) an external SCPD which provides protection against short circuits (this device can be integrated into the SPD). | ||
[[File:Fig J45.jpg|none]] | [[File:Fig J45.jpg|none]] | ||
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The table below shows the characteristics and the arrangements of 3 commonly used technologies. | The table below shows the characteristics and the arrangements of 3 commonly used technologies. | ||
{| class="wikitable | {| class="wikitable" | ||
|- | |- | ||
! Component | ! Component | ||
! Gas Discharge Tube (GDT) | ! Gas Discharge Tube (GDT) | ||
! Encapsulated spark gap | ! Encapsulated spark gap | ||
! Zinc oxide varistor <br> | ! Zinc oxide varistor <br> | ||
! GDT and varistor in series | ! GDT and varistor in series | ||
! Encapsulated spark gap and varistor in parallel | ! Encapsulated spark gap and varistor in parallel | ||
|- | |- | ||
| {{Table_HC2}} | '''Characteristics''' | | {{Table_HC2}} | '''Characteristics''' | ||
! | ! | ||
! | ! | ||
! | ! | ||
! | ! | ||
! | ! | ||
|- | |- | ||
| {{Table_HC2}} | | | {{Table_HC2}} | | ||
| valign="middle" | [[File:Fig J46a.jpg|center|59x128px]] | | valign="middle" | [[File:Fig J46a.jpg|center|59x128px]] | ||
| valign="middle" | [[File:Fig J46b.jpg|center|59x123px]] | | valign="middle" | [[File:Fig J46b.jpg|center|59x123px]] | ||
| [[File:Fig J46c.jpg|center]] | | [[File:Fig J46c.jpg|center]] | ||
| [[File:Fig J46d.jpg|center|39x139px]] | | [[File:Fig J46d.jpg|center|39x139px]] | ||
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| Voltage-switching and -limiting in parallel | | Voltage-switching and -limiting in parallel | ||
|- | |- | ||
| {{Table_HC2}} | '''Operating | | {{Table_HC2}} | '''Operating curves''' | ||
| valign="middle" align="center" colspan="2" | [[File:Fig J46f.jpg|center]] | | valign="middle" align="center" colspan="2" | [[File:Fig J46f.jpg|center]] | ||
| valign="middle" align="center" | [[File:Fig J46g.jpg|none]] | | valign="middle" align="center" | [[File:Fig J46g.jpg|none]] | ||
| {{Table_HC2}} | | | {{Table_HC2}} | | ||
| {{Table_HC2}} | | | {{Table_HC2}} | | ||
|- | |- | ||
| {{Table_HC2}} | '''Application''' | | {{Table_HC2}} | '''Application''' | ||
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'''''Fig. J49:''' Summary performance table'' | '''''Fig. J49:''' Summary performance table'' | ||
'''Note:''' Two technologies can be installed in the same SPD (see | '''Note:''' Two technologies can be installed in the same SPD (see {{FigRef|J50}}) | ||
{{Gallery|J50|The Schneider Electric brand iPRD SPD incorporates a gas discharge tube between neutral and earth and varistors between phase and neutral|221px| | {{Gallery|J50|The Schneider Electric brand iPRD SPD incorporates a gas discharge tube between neutral and earth and varistors between phase and neutral|221px| | ||
Revision as of 09:55, 2 December 2016
The SPD chiefly consists of (see Fig. J48):
1) one or more nonlinear components: the live part (varistor, gas discharge tube, etc.);
2) a thermal protective device (internal disconnector) which protects it from thermal runaway at end of life (SPD with varistor);
3) an indicator which indicates end of life of the SPD;
Some SPDs allow remote reporting of this indication;
4) an external SCPD which provides protection against short circuits (this device can be integrated into the SPD).
Fig. J48: Diagram of a SPD
Technology of the live part
Several technologies are available to implement the live part. They each have advantages and disadvantages:
- Zener diodes;
- The gas discharge tube (controlled or not controlled);
- The varistor (zinc oxide varistor).
The table below shows the characteristics and the arrangements of 3 commonly used technologies.
| Component | Gas Discharge Tube (GDT) | Encapsulated spark gap | Zinc oxide varistor |
GDT and varistor in series | Encapsulated spark gap and varistor in parallel |
|---|---|---|---|---|---|
| Characteristics | |||||
 |
 |
 |
 |
 | |
| Operating mode | Voltage switching | Voltage switching | Voltage limiting | Voltage-switching and -limiting in series | Voltage-switching and -limiting in parallel |
| Operating curves |  |
 |
|||
| Application |
(associated with varistor) |
LV network | LV network | LV network | LV network |
| SPD Type | Type 2 | Type 1 | Type 1 or Type 2 | Type 1+ Type 2 | Type 1+ Type 2 |
Fig. J49: Summary performance table
Note: Two technologies can be installed in the same SPD (see Fig. J50)
Fig. J50 – The Schneider Electric brand iPRD SPD incorporates a gas discharge tube between neutral and earth and varistors between phase and neutral
