The components of a SPD: Difference between revisions
From Electrical Installation Guide
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The SPD chiefly consists of (see '''Fig. | The SPD chiefly consists of (see '''Fig. 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). | ||
<br>[[Image:Fig J45.jpg|left]] <br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>'''''Fig. | <br>[[Image:Fig J45.jpg|left]] <br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>'''''Fig. J48:''' Diagram of a SPD'' | ||
== Technology of the live part''<br>'' == | == Technology of the live part''<br>'' == | ||
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| valign="top" bgcolor="#0099cc" | '''Zinc oxide varistor''' <br> | | valign="top" bgcolor="#0099cc" | '''Zinc oxide varistor''' <br> | ||
| valign="top" bgcolor="#0099cc" | '''GDT and varistor in series''' | | valign="top" bgcolor="#0099cc" | '''GDT and varistor in series''' | ||
| valign="top" bgcolor="#0099cc" | '''Encapsulated spark gap and varistor in | | valign="top" bgcolor="#0099cc" | '''Encapsulated spark gap and varistor in parallel''' | ||
|- | |- | ||
| valign="top" bgcolor="#cccccc" | '''Characteristics''' | | valign="top" bgcolor="#cccccc" | '''Characteristics''' | ||
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'''''Fig. | '''''Fig. J49:''' Summary performance table'' | ||
---- | ---- | ||
Note: Two technologies can be installed in the same SPD (see '''Fig. | Note: Two technologies can be installed in the same SPD (see '''Fig. J50''') | ||
---- | ---- | ||
<br>[[Image:Fig J47.jpg|left]] <br><br><br><br><br><br><br><br><br><br><br>'''''Fig. | <br>[[Image:Fig J47.jpg|left]] <br><br><br><br><br><br><br><br><br><br><br>'''''Fig. J50:''' The Schneider Electric brand PRD SPD incorporates a gas discharge tube between neutral and earth and varistors between phase and neutral'' | ||
---- | ---- | ||
[[zh:浪涌保护器的部件]] | [[zh:浪涌保护器的部件]] | ||
Revision as of 15:26, 20 August 2013
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 ou 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 PRD SPD incorporates a gas discharge tube between neutral and earth and varistors between phase and neutral
