Position of ACH and Thermostat in a LV Panel

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Anonymous Poster	Position of ACH and Thermostat in a LV Panel 07/21/2010 8:41 AM
	Hi Engineers, I have a question regarding anti condensation heaters (ACH) in LV panels. Recently in one of the projects I had installed ACH at the bottom of the enclosure .near the heater (around 30mm above) there were 5 outgoing mcb ...but the client's electrical consultant told me not to install the ACH wherever there are tripping devices....when I asked him the reason he said too much heat can trip the breakers unnecessarily .....so I changed the position of the ACH to top most portion inside the enclosure.....this was agreed by the client...but when the QAQC engineer of the contractor came to do the analysis he strictly told me to install the heater at the bottom and thermostat at the top........now this engineer's firm a worldwide reputed brand...so when I asked him the reason, he said the hot air flow will circulate to the entire DB wen its at the bottom....he said irrespective of the i/p the heater must be at the bottom and thermostat at top............ Now I want to know who is right? And why? Just a little detailed explaination would be helpfull
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mountk2 Power-User Join Date: Jun 2010 Posts: 348 Good Answers: 10	#1 Re: Position of ACH and Thermostat in a LV Panel 07/21/2010 9:20 AM
	QAQC Engineer is correct, when air gets hot it rises up accordingly the ACH Should be there at the bottom and the thermostat should be there at top. Client's Engineer too correctly analyzed that the mcb's are close enough to get direct heat radiation from the ACH instead of convection. Best option for you is to relocate the ACH or the mcb's to increase seperation in a fashion that the ACH still remains at the bottom of the panel. __________________ Knowledge sharing is a WIN-WIN situation
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Tornado Guru Join Date: May 2009 Location: Richland, WA, USA Posts: 21017 Good Answers: 795	#2 Re: Position of ACH and Thermostat in a LV Panel 07/21/2010 10:42 AM
	A fan could spread the heat around and keep it from localizing at the MCBs. If the MCBs are toward one side near the bottom, the ACH could be placed toward the other side. __________________ In vino veritas; in cervisia carmen; in aqua E. coli.
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pvrss1 Participant Join Date: Jun 2010 Posts: 3	#3 Re: Position of ACH and Thermostat in a LV Panel 07/22/2010 7:18 AM
	Hai this is subrahmanyam in knowledge QaQc person is correct. there is a simple logic- hotair will go towards top if you are fixing it on top of the panel hot air will not flow towards inside the panel, it will flow towards outside i mean towords out side of the panel. then the purpose of fixing the ACH is not meeting the requiement. coming to clients point you may keep some sheet between of the ACH and MCB or any tripping device. so his purpose also will solve. i think this will do for you ok C U
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electricalexpert65 Guru Join Date: Oct 2009 Posts: 2061 Good Answers: 169	#4 Re: Position of ACH and Thermostat in a LV Panel 07/22/2010 9:42 AM
	The QA/QC person is correct. ACH is mounted at the bottom of the enclosure so that hot air flows to the top. Thermostat is mounted at the top so that the top temperature is monitored to control the ACH On/Off. As regards the consultant's view that the MCB might trip spuriously due to heat from the ACH, he is also correct, because the overload protcetion device in an MCB is a bi-metal and could operate from external heat too causing spurious triping. Best way out is to have the ACH at the bottom, the Thermostat at the top but shift the MCBs to an area where there would not be any external heat influence.
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Anonymous Poster	#5 Re: Position of ACH and Thermostat in a LV Panel 07/24/2010 3:37 AM
	thank you folks for your answers...... i still have one doubt though.........actually 2 ... 1)why does hot air go frm bottom to top than top to bottom 2) is it safe to place the heater close to outgoin wires.?
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Anonymous Poster	#6 Re: Position of ACH and Thermostat in a LV Panel 07/26/2010 11:20 AM
	Dear Sir, The reply given by QA/QC engineers is right. It is a global practise to keep the thremostat Switch and the heating element at the top and the Space heater at the bottom. Thsi parcatise is follewe for LV AC Board, CB Control Cubilce, LDBs, MKs, BMKs, Trafo. MBs etc. Similarly the Door switches are provided in the Top. Best Wishes, N.Suresh
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Anonymous Poster (2); electricalexpert65 (1); mountk2 (1); pvrss1 (1); Tornado (1)

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