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		<title>Undervoltage - Revision history</title>
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		<updated>2026-05-19T11:58:37Z</updated>
		<subtitle>Revision history for this page on the wiki</subtitle>
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		<id>https://www.designingbuildings.co.uk/w/index.php?title=Undervoltage&amp;diff=287016&amp;oldid=prev</id>
		<title>Designing Buildings: Created page with &quot;[https://www.bsria.com/uk/product/vBGLrE/bsria_power_quality_guide_ag_22000_a15d25e1/ BSRIA Power quality guide (AG 2/2000)] was written by C C Pearson and V Uthayanan and publis...&quot;</title>
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				<updated>2024-10-16T06:26:34Z</updated>
		
		<summary type="html">&lt;p&gt;Created page with &amp;quot;[https://www.bsria.com/uk/product/vBGLrE/bsria_power_quality_guide_ag_22000_a15d25e1/ BSRIA Power quality guide (AG 2/2000)] was written by C C Pearson and V Uthayanan and publis...&amp;quot;&lt;/p&gt;
&lt;p&gt;&lt;b&gt;New page&lt;/b&gt;&lt;/p&gt;&lt;div&gt;[https://www.bsria.com/uk/product/vBGLrE/bsria_power_quality_guide_ag_22000_a15d25e1/ BSRIA Power quality guide (AG 2/2000)] was written by C C Pearson and V Uthayanan and published by BSRIA in July 2000. It states:&lt;br /&gt;
&lt;br /&gt;
Variations in supply voltage outside the normally accepted limits of ± 10% are subdivided according to the length of the variation.&lt;br /&gt;
&lt;br /&gt;
Long duration variations encompass rms deviations at power frequencies for longer than one minute. EN 50160 specifies the steady state voltage tolerances expected on a power system. A voltage variation is considered to be of long duration when the limits are exceeded for more than 3 minutes (the international standards use a period of one minute).&lt;br /&gt;
&lt;br /&gt;
Long duration variations can be:&lt;br /&gt;
&lt;br /&gt;
* sustained interruptions&lt;br /&gt;
* undervoltages&lt;br /&gt;
* overvoltages.&lt;br /&gt;
&lt;br /&gt;
An undervoltage is a decrease in the rms ac voltage to less than 90% at the power frequency for a duration longer than 3 minutes.&lt;br /&gt;
&lt;br /&gt;
Undervoltages are the result of the events which are the reverse of the events that cause overvoltages. A load switching on or a capacitor bank switching off can cause an undervoltage until voltage regulation equipment on the system can bring the voltage back to within tolerances. Overloaded circuits can also result in undervoltages.&lt;br /&gt;
&lt;br /&gt;
--[[User:BSRIA|BSRIA]]&lt;br /&gt;
&lt;br /&gt;
= Related articles on Designing Buildings =&lt;br /&gt;
&lt;br /&gt;
* Alternating current and direct current&lt;br /&gt;
* Ampere.&lt;br /&gt;
* BSRIA articles on Designing Buildings.&lt;br /&gt;
* BSRIA definitions.&lt;br /&gt;
* BSRIA.&lt;br /&gt;
* Overvoltage.&lt;br /&gt;
* Power.&lt;br /&gt;
* Sustained interruptions.&lt;br /&gt;
* Voltage.&lt;br /&gt;
* Watt.&lt;br /&gt;
&lt;br /&gt;
[[Category:DCN_Definition]] [[Category:Definitions]]&lt;/div&gt;</summary>
		<author><name>Designing Buildings</name></author>	</entry>

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