လြန္ခဲ႔ေသာတစ္ႏွစ္ခန္႔က ကၽြန္ေတာ္တာဝန္ယူလုပ္ခဲ႔ရေသာ ပေရာ႔ဂ်က္တစ္ခုတြင္အမွားျပင္ဆင္ျခင္းျပဳလုပ္ရာမွ ကၽြန္ေတာ႔စူပါဗိုက္ဇာ
ဓါတ္လိုက္ခံရျပီး လက္က်ိဳးသြားပါတယ္။ အမွားျပင္ေသာ soft starter က switch board ရဲ႕အေပၚဆံုးအကန္႔မွာရွိတာ
ေၾကာင္႔ အနီးမွာရွိေသာေကဘယ္ဒရမ္ကိုခုျပီး တက္လုပ္ရပါတယ္။ အဲဒီအလုပ္ကကၽြန္ေတာ္လုပ္ရမွာပါ။
ျဖစ္ခ်င္ေတာ႔အဲဒီေန႔မွ သူ႕ဘက္ဆိုဒ္ကအလုပ္ပါးလို႔ ပထမဆံုးလိုက္လာတာပါ။ ကၽြန္ေတာ္႔ကိုလိုက္ပို႔တယ္ဆိုရင္လဲမမွားပါဘူး။ အလုပ္ လုပ္ေတာ႔ သူကပဲအဲဒီေပၚတက္ျပီး ကၽြန္ေတာ္႔ကိုပစၥည္းယူခိုင္းပါတယ္။ Incoming Breaker ကိုေတာ႔ပိတ္ထားျပီးပါျပီ။ ပစၥည္းယူျပီးျပန္လာေတာ႔ သူကျဖဳတ္သင္႔တာျဖဳတ္တပ္သင္႔တာတပ္လုပ္ေနပါျပီ။
ကၽြန္ေတာ္လဲသူလိုခ်င္တဲ႔ Relay ေပးေနတုန္း ငနဲသား(တရုတ္လူမ်ိဳး)ဓါတ္လိုက္ပါေလေရာ။ အသံလဲမထြက္ႏိုင္ဘူးကၽြန္ေတာ္လဲထူပူျပီးဘာလုပ္ရမွန္းမသိ ေဘးမွာလဲဘယ္သူမွမရွိဘူး။ ညေန ၃ နာရီဆိုေတာ႔အလုပ္သမားေတြ လက္ဘက္ရည္ေသာက္နားခ်ိန္ေလ။ဘယ္ဘက္တံေတာင္က ေဘာ္ဒီမွာေထာက္ျပီး ညာဘက္လက္က control ဝါယာကိုင္ျပီး ေအာက္ကိုလဲျပဳတ္မက်ဘဲကိုယ္႔ယိုးကားယားျဖစ္ေနတာ။ ေနာက္ေတာ႔မထူးဘူး ဆိုျပီးသူ႔အကၤ်ီအစကိုပဲ ဆြဲခ်လိုက္လိုက္မိတယ္။ ေအာက္ကိုျပဳတ္က်ေတာ႔ အတည္႔ပါပဲ။ဆြဲထူေတာ႔လက္ေမာင္းအရင္းက ေယာင္ေနျပီ။ ၆ လေဆးခြင္႔ယူလိုက္ရတယ္။
Main Breaker ကိုပိတ္ေပမယ္႔ control MCB ကိုမပိတ္မိလို႔ဓါတ္လိုက္တာပါ။ သူမရွိေတာ႔ သူ႔ေနရာကို တာဝန္ယူျပီးဆိုဒ္
ေတာ္ေတာ္မ်ားမ်ား သြားလိုက္ရတယ္။ ကၽြန္ေတာ္႔အတြက္ကေတာ႔ လုပ္ငန္းအေတြ႔အၾကံဳရျပီး သူေဌးရဲ႕ယံုၾကည္မႈ႔ရလိုက္တာ အျမတ္
ပါပဲ။ :D
ကၽြန္ေတာ္တို႔စက္ရံုကစားအုန္းဆီစက္ရံူေတာ္ေတာ္မ်ားမ်ားရဲ႕ switch board ေတြလုပ္ပါတယ္။ဂ်င္နေရတာေတြ အတူယွဥ္တြဲ
တာကအစ ေမာ္တာ စတာတာေတြလုပ္ပါတယ္။ အဲဒီမွာလူသိနည္းလွတဲ႔ grounding or earthing ရဲ႕အေရးပါပံုကိုသတိျပဳ
မိလာပါတယ္။
ဂ်င္နေရတာေတြယွဥ္တြဲတဲ႔အခါမွာလဲ earthing ကအေရးပါလွပါတယ္။ လွ်ပ္စစ္ပစၥည္းမ်ားမေတာ္တဆ ေရွာ႔ျဖစ္ပ်က္စီးျခင္း၊ မေတာ္တဓါတ္လိုက္မႈ႔ အႏၱရယ္ႏွင္႔တစ္ခ်ိန္ထဲမွာပဲ ပါဝါတည္ျငိမ္မႈ႕ကို ျဖစ္ေစပါတယ္။ကၽြန္ေတာ္ေလ႔လာျဖစ္တဲ႔ စာအုပ္ထဲက အေၾကာင္းအရာမ်ားကို နည္းနည္းျခင္းၾကိဳးစားေရးသြားပါ႔မယ္။ အမွားရွိရင္ ေထာက္ျပသင္ေပးၾကပါလို႔ ေျပာခ်င္ပါတယ္။
Neutral Grounding
Power system တစ္ခုတြင္လွ်ပ္စီးသယ္ေဆာင္မႈ႔ မရွိေသာအစိတ္အပိုင္း(လွ်ပ္စစ္အသံုးအေဆာင္ပစၥည္း၏ေဘာ္ဒီ၊ ဖရိမ္)
သို႕မဟုတ္လွ်ပ္စီးသယ္ေဆာင္ေသာအစိတ္အပိုင္း(ဥပမာ star-connected system တစ္ခု၏ neutral point ႏွင္႔
Transformer တစ္ခု၏တစ္ဆင္႔ခံဝါယာ တစ္စ)တို႔အား စြတ္ဆိုမႈ႕ရွိေသာေျမၾကိးသို႔ ဆက္သြယ္ေပးျခင္းကို grounding or
earthing လို႔ေခၚပါတယ္။ ထိုကဲ႔သို႔ဆက္သြယ္ရာတြင္ တိုက္ရိုက္ သို႔မဟုတ္ resistor, circuit breaker အစရွိသည္တို႔အား လိုအပ္ခ်က္အေျခအေနေပၚမႈတည္၍ အသံုးျပဳပါတယ္။ ေယဘူရအားျဖင္႕ ဥပေဒသႏွစ္ရပ္နဲ႔ေတြ႔ရမွာပါ။
၁။ Neutral point အား ground ခ်ထားေသာ star-connected system တစ္ခုတြင္ circuit breaker
အထြက္ပိုင္းေဖ႔စ္ၾကိဳးတစ္ခုခု ႏွင္႔ ground တို႔ၾကား earth fault ျဖစ္ေသာအခါၾကီးမားေသာ လွ်ပ္စီးျဖစ္ေပၚေစ၍
circuit breaker မွပါတ္လမ္းကို ျဖတ္ေတာက္ကာကြယ္ေပးျခင္း။
၂။ လွ်ပ္စစ္အသံုးအေဆာင္ပစၥည္းတို႔၏ ေဘာ္ဒီ အား earth သြယ္တန္းထားျခင္းအားျဖင္႔ အသံုးျပဳသူအားလွ်ပ္စစ္အႏၱရယ္မွ
ကာကြယ္ေပးျခင္းတို႔ျဖစ္ပါသည္။
Electrical ႏွင္႔ electronic ဆားကစ္တို႔တြင္ common points တို႔အား ၎တို႔၏ သတၱဳကိုယ္ထည္ႏွင္႔ ဆက္သြယ္ ေပးျခင္းကို chasis ground သို႔မဟုတ္ circuit ground ဟုေခၚပါသည္။ circuit ground သည္ေျမၾကီးသို႔ဆက္
သြယ္ထားျခင္း၊ မထားျခင္းႏွစ္ခုလံုး ျဖစ္ႏိုင္သည္။(ဥပမာ ေမာ္ေတာ္ကားသို႔မဟုတ္ ဂ်င္နေရတာမ်ားတြင္ အႏုတ္ၾကိဳးအားေဘာ္ဒီ
တြင္ဆက္သြယ္ထားျခင္း)
Grounding or Earthing
Grounding or Earthing ကိုခြဲျခမ္းစိတ္ျဖာၾကည္႔မယ္ဆိုရင္
၁။ Equipment grounding ၂။ System grounding ဆိုျပီးေတြ႔ရမွာပါ။
(ဆက္လက္ေဖၚျပပါမည္)
ကိုးကား(principles of power system & A textbook of electrical technology)
ဆီအုန္းစက္ရုံမ်ားမွာရွိတဲ႔ fibre cyclone fan ေတြဟာ screw press မွထြက္လာတဲ႔ အဆံနဲ႔အမွ်င္တို႔ကိုခြဲျခားေပး ဖို႔အတြက္အသံုးျပဳပါတယ္။ အမွ်င္မ်ားထက္ပိုမိုေလးလံတဲ႔ အဆံတို႔ကိုထားခဲ႔ျပီး ပန္ကာနဲ႔ဆက္ထားတဲ႔ျပြန္အတိုင္း စုပ္ယူျခင္းခံရပါ တယ္။ အမွ်င္မ်ားကိုစုပ္ယူႏိုင္ဖို႔ သတ္မွတ္ထားတဲ႔ RPM 2500 ခန္႕ရွိရမွာျဖစ္ပါတယ္ ။ဒါေၾကာင္႔ ပန္ကာနဲ႔ဆက္ထားတဲ႔
ေမာ္တာရဲ႕စတင္လည္ပတ္ခ်ိန္မွာ ပံုမွန္ထက္အမ္ပီယာပိုမိုဆြဲယူပါတယ္။ အက်ိဳးဆက္အားျဖင္႔
၁။ေအာ္တိုထရမ္စ္ေဖာ္မာေလာင္ျခင္း ၂။မိန္းဘေရကာ ျပဳတ္က်ျခင္းတို႔ ျဖစ္တတ္ပါတယ္။
၁။ ေအာ္တိုထရမ္စေဖာ္မာ ေလာင္တဲ႔ေနရာကို စစ္ေဆးၾကည္႔ေတာ႔ တက္ပင္းရဲ႕ အဆက္ေနရာမွာျဖစ္ေနတာေတြ႔ရပါတယ္။ ခဲေဆာ္တာ
လံုေလာက္ေအာင္ေကာင္းမြန္ျခင္းမရွိဘူးလို႔ ေတြးထင္ပါတယ္။ တစ္ခါတစ္ရံမွာလဲ terminal မွာမူလီေတြေခ်ာင္ေနရင္လဲ ျဖစ္တတ္ပါ
တယ္။
၂။ MCC panel ေတြမွာ over current relay တပ္လို႔အဆင္မေျပပါ။ Earth fault relay ဆိုရင္လံုေလာက္ျပီထင္ပါ
တယ္။ စတာတာတိုင္းမွာ ေမာ္တာပရုိတက္ရွင္း အတြက္ သာမယ္အိုဗာလုတ္ ပါရွိျပီးျဖစ္ပါတယ္။ တစ္ခါၾကံဳဘူးပါတယ္ ကြန္ေဆာက္တန္႔ကဆြဲေပးလိုက္တဲ ဒီဇိုင္းတစ္ခုပါ။1*75kw ဖိုင္ဘာဆိုက္ကလံုး၊2*7.5kw ကြန္ေဗယာ နဲ႔ 2*4kwကြန္ေဗယာတို႔ပါ။ မိန္းဘေရကာကို 200 Amp တပ္ထားပါတယ္။ over current relay ပါသံုထားပါေသးတယ္။
'မရဘူး'လို႔ အထက္ကိုေျပာေတာ႔ ဒါ ကြန္ေဆာက္တန္႔ ေပးတာတဲ႕။ ဒါနဲ႔ ဒီအတိုင္းပဲ ထြက္သြားတယ္။ မၾကာပါဘူး ဘေရကာ
ျပဴတ္က်တယ္ ဆိုျပီး ဖုန္းဝင္လာတာပါပဲ။
ေနက္ေန႔လိုက္သြားျပီးေရာက္ေတာ႔ စမ္းလိုက္တယ္။ ပထမအဆင္႔ ၅၅% မွာ အမ္ပီယာ ၂၀၀ ေက်ာ္ ဒုတိယအဆင္႔၇၅%အေျပာင္း
မွာ over current relay ကဘေရကာကို ျဖဴတ္ခ်လိုက္ျပီ။ Boss ကိုဖုန္းဆက္ အက်ိဳးအေၾကာင္းေျပာျပျပီး Main Con.
ဆီဖုန္းဆက္ေတာ႔ 'ဘာလို႔မရရမွာလဲ' တဲ႔ စုစုေပါင္း98kw ကို AMP 200 ဝန္းက်င္ပဲရွိတာတဲ႔။ ေကာင္းေရာဗ်ာ။
ဖိုက္ဘာဆိုက္ကလံုးေမာ္တာရဲ႕ အေျခအေနေတြ ေတာ္ေတာ္ရွင္းျပယူလိုက္ရတယ္။
BOSS ကေတာ႔ဝမ္းသာမွာေပါ႔။ ပိုက္ပိုက္ထပ္ရမွာကိုး။
ညအိပ္ျပီး 250 AMP ဘေရကာေစာင္႕ ေနာက္ေန႔ တပ္၊ over current relay ကိုလဲ ျဖဳတ္ပစ္လိုက္တယ္။အားလံုးျပီးေတာ႔
စမ္းလိုက္တယ္။ ပထမအဆင္႔ အမ္႔ ၂၀၀ ေက်ာ္ ဒုတိယ အမ့္၂၅၀မီတာရဲ႔ မွ်ားတံ ဂိတ္ဆံုးေရာက္သြားတယ္။ တတိယ ၁၀၀% အ
ေျပာင္းမွာ စက္ရုံကို ဓါတ္အားေပးထားတဲ႔ ဒီဇယ္ဂ်င္နေရတာရဲ႕ ဘေရကာျပဴတ္က်သြားတယ္။ စက္ရုံအေဟာင္းကို ျပန္ျပင္တာဆို
ေတာ႔ ဂ်င္နေရတာတို႕ ေရေႏြးေငြ႔တာဗိုင္း တို႕ Main Board တို႕ကို အေဟာင္းေတြျပန္သံုးထားတာ။ Capacitor Bank
ေတြဆိုရင္ ေကာင္းေကာင္းအလုပ္မလုပ္ေတာ႔ဘူး။ 250 kw ဒီဇယ္ဂ်င္နေရတာႏွစ္လံုးနဲ႔ 1600kw တာဗိုင္းတို႔ကလဲေဟာင္းေနျပီ။
ဘေ၇ကာျပဳတ္က်တဲ႕အင္ဂ်င္က 250kwပါ။ စက္ရုံမလည္ပဲစမ္းရုံဆိုေတာ႔ အင္ဂ်င္တစ္လံုးပဲေမာင္းထားျပီးမႏိုင္လို႕ over current ျဖစ္တာပါ။ ေနာက္ထပ္အင္ဂ်င္တစ္လံုး တြဲခိုင္းျပီးထပ္စမ္းေတာ႔အဆင္ေျပသြားတယ္။
soft starter ေဈးေတြခ်ိဳလာျပီး ေၾကးနီေဈးတက္လို႔ ထရမ္ေဖာ္မာေဈးၾကီးေနတဲ႔အခ်ိန္(soft starter ေဈးနဲ႔ Auto
trans တစ္စံုရဲ႕ ကြာျခားေဈးႏူန္း အရမ္းမမ်ားတဲ႔ ကာလမွာ)soft starter ကိုဘာေၾကာင္႔မသံုးၾကလဲဆိုတာ စဥ္းစားမရပါ။
ကၽြန္ေတာ္လဲ႔ ပို႔စ္မတင္ျဖစ္တာ ၾကာပါျပီ။ လာလည္တဲ႔ မိတ္ေဆြေရာင္ရင္း အားလံုးကို အႏူးအညြတ္ေတာင္းပန္ပါတယ္။
တစ္ေလာက ေအာ္တိုထရမ္စေဖာ္မာ ေလာင္သြားတယ္ဆိုလို႔ သြားလဲခဲ႔ရတယ္။ မေလးရွားႏိုင္ငံ ပါဟန္းျပည္မွာရွိတဲ႔ စားအုန္းဆီ စက္ရုံတစ္ခုမွာပါ။ ဆီအုန္းသီးေတြကို ၾကိတ္လို႕ထြက္လာတဲ႔ အဆံနဲ႔ ဖိုက္ဘာအမွ်င္တို႔ ေရာေနတာကို ခြဲထုတ္ေပးတဲ႔ Fibre cyclone fan ရဲ႕ေအာ္တိုထရမ္စေဖာ္မာ ေလာင္သြားတာပါ။ ေရာက္ေရာက္ခ်င္း ေလာင္သြားတဲ႔ ၃ေဖ႔စ္ ၄၅ကီလိုဝပ္ ရွိတဲ႔ ေမာ္တာရဲ႕ ေအာ္တိုထရမ္စေဖာ္မာကို ျဖဳတ္ အသစ္လဲတပ္လိုက္ပါတယ္။ ေမာ္တာက ၄၅ကီလိုဝပ္ ဆိုေပမယ္႔ ေအာ္တိုတရမ့္စ္ကို ဟဲဗီးဂ်ဳတီ အေနနဲ႔ တစ္ဆင္႔ျမွင္႔ ၅၅ကီလိုဝပ္ သံုးထားတာပါ။ ေနာက္လဲတဲ႔ တဆင္႔ထပ္ျမွင္႔ျပီး ၆၅ကီလိုဝပ္ခံႏိုင္ရည္ရွိတဲ႔ ေအာ္တိုထရမ့္စ္ကို တပ္ဆင္ျပီးေတာ႔ ဝါယာရင္းနဲ႔ အလုပ္လုပ္ပံု မွန္မမွန္ကို FREE RUN အေနနဲ႔ ေမာ္တာ ေကဘယ္ကိုျဖဳတ္ျပီး စမ္းလိုက္ေတာ႕ အားလံုး အိုေကပါတယ္။ ေမာ္တာရဲ႕အျပစ္အနာ အဆာကို မက္ဂါသံုးျပီး ရွာေတာ႔လဲ အိုေကပါပဲ။ ဒါနဲ႔အားလံုးျပန္တပ္ျပီး အဆင္သင္႔ ဲျဖစ္ေတာ႔ ဘေရကာကို ဖြင္႔ျပီး စတာတာခလုပ္ကို ႏိွပ္ လိုက္ပါ တယ္။ 
ဖြင္႔ဖြင္႔ခ်င္းပဲ ေအာ္တိုထရမ့္စ္က မီးေတာက္ေတြထြက္လာလိုက္တာ ေတာ္ေတာ္ျငိမ္းယူရတယ္။ ညေနကလဲေစာင္းေနျပီေလ။ ျပန္ဖို႔အခ်ိန္ကလဲ ရွိေသးေတာ႔ ေခါင္းကိုက္သြားတာေပါ႔။ မတတ္ႏိုင္ဘူးေလျပန္ရမဲ႔ ခရီးကလဲ ၄နာရီကားေမာင္းရမွာ ေအာ္တိုထရမ့္စ္
ကလဲ အပိုမပါဘူး။ စက္ရုံတာဝန္ခံ အင္ဂ်င္နီယာ ကလဲ ပူညံပူညံ။ ေတာ္ေသးတယ္ စက္ရံုကအသစ္ျပီးကာစ ဆိုေတာ႔ ေနာက္အပတ္ ရက္ခ်ိန္းယူျပီး ျပန္ခဲ႔ရတယ္။
ေခါင္းလဲစားသြားတာ အိပ္ေတာင္မေပ်ာ္လို႔ ေတာ္ေတာ္လုပ္ယူရတယ္:D။ ေသေသခ်ာခ်ာ စဥ္စားၾကည္႔ေတာ႔ ဝါယားရင္းလဲ အိုေက
ကြန္နက္ရွင္းလဲ အိုေကဆိုေတာ႔ ေမာ္တာရဲ႕ ဝန္အားကို သံသယျဖစ္မိတယ္။ ရင္တထိတ္ထိတ္နဲ႔ေပါ႔။ ဘာမွမဟုတ္တဲ႔ႏိုင္ငံျခားသား
ျမန္မာတစ္ေယာက္ကို မယံုရဲဘူးနဲ႕တူပါတယ္။
ဒါနဲ႔ေနာက္အပတ္သြားေတာ႔ ထံုးစံအတိုင္းျဖဳတ္တပ္ျပီး ေမာ္တာအပိုင္းကို သြားၾကည္႔ေတာ႔ ေမာ္တာက ၄ပိုး အာပီအမ္၁၅၀၀၊
ပူလီနဲ႔တြဲ ထားတဲ႔ ပန္ကာရဲ႕ အာပီအမ္က ၂၅၀၀ ၊ အဲဒီေတာ႔ ေမာ္တာရဲ႕ပူလီက ေသးျပီး ပန္ကာရဲ႕ပူလီက ၾကီးေနပါတယ္။
အဲဒီမွာ သူ႔ရဲ႕ ဝန္အားကို စဥ္စားရေတာ႔မွာပါ။ ဒါနဲ႔ မက္ကယ္နီကယ္အင္ဂ်င္နီယာ အက်ိဳးအေၾကာင္းေျပာျပေတာ႔ အဲဒီအတိုင္းပဲတဲ႔။
ဒါနဲ႔ပေရာဂ်က္မန္ေနဂ်ာဆီကို ဖုန္းဆက္ေတာ႔ ေမာ္တာလဲေပးရမလား လို႔ေတာ႕ ေျပာပါတယ္။ ေမာ္တာအပ္ဂရိတ္လုပ္ရင္ ဘေရကာတို႔ ကြန္တပ္တာတို႔ ေကဘယ္တို႔ ေနာက္ဆက္တြဲအလုပ္ေတြ ပိုလာေတာ႔မယ္ေလ။ ၾကိဳးစားၾကည္႔မယ္ေပါ႔။
၁။ပူလီၾကိဳးတင္းေနတာ ကိုေလွ်ာ႔ခိုင္းလိုက္ပါတယ္။
၂။ ေအာ္တိုထရမ္စေဖာ္မာက တက္ပင္း ၅၅% နဲ႕၇၅% ေနရာမွာ ၅၅%က ေမာ္တာရဲ႕ဒိုင္းနမစ္ အေျခအေနမွာ အမ္ပီယာ
ပိုဆြဲမွာျဖစ္လို႕ ေအာ္တိုထရမ့္စ္ရဲ႕ ၅၅%ကို ၆၅% ေျပာင္းလိုက္ပါတယ္။
၃။ ၆၅% မွ ၇၅% တက္ပင္းေျပာင္းတဲ႔ Timer ကို ၅စကၠန္႔ ေျပာင္းလိုက္ပါတယ္ ။၇၅%မွ ၁၀၀% ေျပာင္တဲ႔ Timer ကို
၃စကၠန္႔ေျပာင္းလိုက္ပါတယ္။
ျပီးေတာ႔ရင္ထိတ္ထိတ္နဲ႔ စမ္းလိုက္ပါတယ္။
ၾကည္႔လိုက္ေတာ႔ ပထမအဆင္႔ အမ္ပီယာ ၅၀၀ ေက်ာ္သြားတယ္။ ဒုတိယ ခုန္တက္ျပီး ပံုမွန္ျဖစ္သြားတယ္။
ရင္ထဲအလံုးၾကီးလဲပံုမွန္ျဖစ္သြားတယ္။
ဆီအုန္းစက္ရံုရဲ႕ဘိြဳင္လာပံုေလးေတြတင္ေပးလိုက္တာပါ။ေလာင္စာကေတာ႔ ဆီအုန္းအမွ်င္နဲ႔ အခြံတို႔ပဲျဖစ္ ပါတယ္။အသံုးဝင္လိမ္႔မယ္လို႔ထင္ပါတယ္။
A modern steam power station is highly complex and has numerous equipment and auxiliaries. However, the most important constituents of a steam power station are:
1. Steam generating equipment 2. Condenser 3. Prime mover 4. Water treatment plant
5. Electrical equipment.
(Boiler control board)
1. Steam generating equipment. This is an important part of steam power station. It is concerned with the generation of superheated steam and includes such items as boiler, boiler furnace, superheater ,economiser, air pre-heater and other heat reclaiming devices.
(i) Boiler . Aboiler is closed vessel in which water is converted into steam by utilising the heat of coal combustion. Steam boiler are broadly classified into the following two types :
(a) Water tube boilers (b) Fire tube boilers
( Water tube boiler)
In the water tube boiler, water flows through the tubes and the hot gases of combustion flow over these tubes. On the other hand, in a fire tube boiler,the hot products of combustion pass through the tube surrounded by water. Water tube boilers have a number of advantages over fire tube boilers viz., require less
space, smaller size of tube and drum, high working pressure due to small drum, less liable to explosion etc. Therefore, the use of water tubes boilers has become universal in large capacity steam power stations.
(Drum Level Controller)
(ii) Boiler furnace. A boiler furnace is a chamber in which fuel is burnt to liberate the heat energy. In addition
it provides support and enclosure for the combustion equipment i.e., burners. The boiler furnace wall are made
of refractory materials such as fire clay, silica, kaolin etc.These materials have the property to resist change of
shape, weight or physical properties at high temperatures. There are following three types of construction of furnace walls:
(a) Plain refractory walls
(b) Hollow refractory walls with an arrangement for air cooling
(c) Water walls
The plain refractory walls are suitable for small plants where the furnace temperature may not be high. However, in large plants, the furnace temperature is quite high (The size of furnace has to be limited due to
space, cost and other considerations. This means that furnace of a large plant should develop more kilocalories per square metre of furnace which implies high furnace temperature.) and consequently,the refractory material may get damaged. In such cases, refractory walls are made hollow and air is circulated
through hollow space to keep the temperature of the furnace walls low. The recent development is to use water walls.These consist of plain tubes arrange side by side and the inner face of the refractory walls. The tubes are connected to the upper and lower headers of the boiler. The boiler water is made to circulate
through the tubes. The water walls absorb the radiant heat in the furnace which would otherwise heat up the
furnace walls.
(Fibre &Shell)
(iii) Superheater. A superheater is a device which superheats the steam i.e., it raises the temperature of steam above boiling point of water. This increases the overall efficiency of the plant. A superheater consist of a group of tubes made of special alloy steels such as chromium-molybdenum. These tubes are heated by heat
of flue gases during their journey from the furnace to the chimney. The steam produced in the boiler is led through the superheater where it is superheated by the heat of flue gases. Superheater are mainly classified into two types according to the system of heat transfer from flue gases to steam viz.
(a) Radiant superheter (b)Convection superheater
The radiant superheater is placed in the furnace between the water walls and receives heat from the burning
fuel through radiation process. It has two main disadvantages. Firstly,due to high furnace temperature, it may
get overheated and, therefore, requires a careful design. Secondly the temperature of superheater falls with increase in steam output. Due to this limitations, radiant superheater is not finding favour these days. On the other hand, a convection superheater is placed in the boiler tube bank and receives heat from flue gases entirely through the convection process.It has the advantage that temperature of superheater increases with
the increase in steam output. For this reason, this type of super is commonly used these days.
(iv) Economiser. It is device which heats the feed water on its way to boiler by deriving heat form flue gases.
This results in raising boiler efficiency, saving in fuel and reduced stresses in the boiler due to higher temperature of feed water. An economiser consists of a large number of closely spaced parallel steel tubes
connected by header of drums. The feed water flows through these tubes and the flue gases flow outside. A
part of the heat of flue gases is transferred to feed water,thus raising the temperature of the latter.
(v) Air pre-heater. Superheater and economisers generally cannot fully extract the heat from flue gases.
Therefore, pre-heater are employed which recover some of the heat in the escaping gases. The function of
an air pre-heater is to extract heat from the flue gases and give it to the air being supplied to furnace for coal combustion. This raises the furnace temperature and increases the thermal efficiency of the plant.Depending upon the method of transfer of heat from flue gases to air, air pre-heaters are divided into the following two
classes:
(a) Recuperative type (b) Regenerative type
The recuperative type air heater consists of a group of steel tubes.the flue gases are passed through the tubes while the air flows externally to the tubes. thus heat of flue gases is transferred to air. The regenerative
type air pre-heater consists of slowly moving drum made of corrugated metal plates. The flue gases flow
continuously on one side of the drum and air on the other side. This action permits the transference of heat of flue gases to the air being supplied to the furnace for coal combustion.
(Induced draught fan & Chimney)
2.Condensers. A condenser is a device which condenses the steam at the exhaust of turbine. It serves two
important functions.Firstly, it creates a very low ( By liquidation steam at the exhaust of turbine, a region of
emptiness is created. This results in a very low pressure at the exhaust of turbine.) pressure at the exhaust of
turbine, thus permitting expansion of the steam in the prime mover to very low pressure. This helps converting
heat energy of steam into mechanical energy in the prime mover. Secondly, the condensed steam can be used as feed water to the boiler. There are two types of condensers, namely:
(i) Jet condenser (ii) Surface condenser 
( A Surface Condenser )
In a jet condenser, cooling water and exhausted steam are together. Therefore , the temperature of cooling
water and condensate is the same when leaving the condenser. Advantages of this type of condenser are :
low initial cost, less flow area required, less cooling water required and low maintenance charges. However,
its disadvantage are: condensate is wasted and high power is required for pumping water.
In a surface condenser, there is no direct contact between cooling water and exhausted steam. It consists of a bank of horizontal tubes enclosed in a cast iron shell. The cooling water flows through the tubes and exhausted steam over the surface of the tubes. The steam gives up its heat to water and is itself condensed.
Advantage of this type of condenser are : condensate can be used as feed water, less pumping power required and creation of better vacuum at the turbine exhaust. However, disadvantage of this type of condenser are : high initial coast, requires large floor area and high maintenance charges.
3. Prime mover. The prime mover converts steam energy into mechanical energy. There are two type of steam prime mover viz., steam engines and steam turbines. A steam turbine has several advantages over
a steam engine as a prime mover viz., high efficiency, simple construction, higher speed, less floor area requirement and low maintenance cost. Therefore, all modern steam power stations employ steam turbines as
prime mover.
Steam turbines are generally classified into two type according to the action of steam moving blades viz.,
(i)Impulse turbines (ii) reaction turbines
In an impulse turbine, the steam expands completely in the stationary nozzles (or fixed blades), the pressure over the moving blades remaining constant. In doing so , the steam attains a high velocity and impinges against the moving blades. This results in the impulsive force on the moving blades which sets the rotor rotating. In a reaction turbine, the steam is partially expanded in the stationary nozzles, the remaining expansion takes place during its flow over the moving blades. The result is that the momentum of the steam
causes a reaction force on the moving blades which sets the rotor in motion.
(Impulse turbine)
4. Water treatment plant. Boiler require clean and soft water for longer life and better efficiency.However, the
source of boiler feed water is generally a river or lake which may contain suspended and dissolved impurities,
dissolved gases etc. Therefore, it is very important that water is first purified and softened by chemical treatment and then delivered to the boiler.
The water from the source of supply id stored in storage tanks.The suspended impurities are removed through
sedimentation, coagulation and filtration. Dissolved gases are removed by aeration and degasification. The water is 'softened, by removing temporary and permanent hardness through different chemical processes. The
pure and soft water thus available is fed to the boiler for steam generation.
( Water treatment plant )
5. Electrical equipment. A modern power station contains numerous electrical equipment. However, the most important items are:
(i) Alternators. Each alternator is coupled to a steam turbine and converts mechanical energy of turbine into
electrical energy. The alternator may be hydrogen or air cooled. The necessary excitation is provided by means of main and pilot exciters directly coupled to the alternator shaft.
(ii) Transformers. A generation station has different types of transformers, viz.,
(a) main step -up transformers which step-up the generation voltage for transmission of power.
(b) station transformers which are used for general service (e.g., lighting) in the power station.
(c) auxiliary transformers which supply to individual unit-auxiliaries.
(iii)Switchgear. It houses such equipment which locates the fault on the system and isolate the faulty part from
the healthy section. It contains circuit breakers, relays, switches and other control devices. 
(Main switch Board)
(Principles Of Power System By V.K MEHTA And ROHIT MEHTA)
Low voltage system , Main Switch Board တစ္ခုတြင္ ပါဝင္ေသာ အဓိကအစိတ္ အပိုင္းမ်ားမွာ
၁။ ကိုယ္ထည္ (Body, Frame)
၂။ ေကဘယ္အဝင္ပိုင္း (Main breaker)
၃။ Metering & Protection
၄။ Bus Bar
၅။ ပါဝါျဖန္႔ေဝရာအပိုင္း(Outgoing breakers)
၆။ ကာပယ္စီတာဘဏ္႔ (Capacitor Bank)
တို႔ျဖစ္ပါတယ္။
၁။ ကိုယ္ထည္ပိုင္း (Body, Frame)
ကိုယ္ထည္ပိုင္းကိုေတာ႔၂မီလီမီတာအထူ sheet metal နဲ႔ျပဳလုပ္ထားျပီး ေဆးကေတာ႔ Expoxy powder coding ပါ။ ေပါင္ဒါကို အေျခာက္မႈတ္ၿပီးမွ အပႈခ်ိန္ ၂၀၀ ဒီဂရီစင္တိဂရိတ္နဲ႔ ၄၅ မိနစ္ အလံုပိတ္အခန္း ထဲထည္႔ၿပီးေပါင္းရပါတယ္။ တစ္စစီ အစိတ္အပိုင္းမ်ားျဖဳတ္တတ္၍ရေသာ modular type ျဖစ္ပါတယ္။
၂။ ေကဘယ္အဝင္ပိုင္း(Main Breaker) 
Main Breaker ကိုႏွစ္မ်ိဳးသံုးပါတယ္။ အမ္ပီယာ ၁၂၀၀ ထိ MCCB (Moulded Case Circuit Breaker)ကို
သံုးၿပီး အထက္ကိုေတာ႔ ACB (Air Circuit Breaker)ကိုသံုးပါတယ္။ ကၽြန္ေတာ္တို႔စက္ရံုကေတာ႔ Low voltage
မွာ အမ္ပီယာ ၆၀၀၀ ထိျပဳလုပ္ပါတယ္။ ဒီအပိုင္းကေတာ႔ ထရန္စ္ေဖာ္မာ သို႔မဟုတ္ ဂ်င္နေရတာ မွ ပါဝါ အဝင္
ေကဘယ္လက္ခံတဲ႔ အပိုင္းပါ။
၃။ Metering & Protection
ပါဝါ ဆပလိုင္းရဲ႕ အဝင္ ဗို႔ေတ႔ voltage ၊ဖရီကြမ္စီ Hz သံုးစြဲ အမ္ပီယာ Amp, ကီလိုဝပ္Kw,ကီလိုဝပ္ ဟာဝါ
Kwh, ပါဝါဖက္တာ PF အစရွိသည္တို႔အားသိရွိႏိုင္ရန္ အဆိုပါမီတာမ်ားကို တပ္ဆင္အသံုးျပဳပါတယ္ ။
Bus Bar protection relay မ်ားျဖစ္တဲ႔ Over current နဲ႔ Earth fault relay ကိုလဲဒီအပိုင္းမွာပဲ တပ္ဆင္ပါ တယ္ ။ Current transformer မ်ားကိုေတာ႔ အဝင္ Main Breaker နဲ႔ အထြက္ Breakers မ်ား ၾကား Bus Bar မွာတပ္ဆင္ပါတယ္။
၄။Bus Bar
Bus Bar ကေတာ႔ ေၾကးနီျဖင္႔ျပဳလုပ္ထားၿပီး Outgoing Breakers မ်ားသို႔ ပါဝါ ျဖန္႔ျဖဴးေပးပါတယ္။ ေၾကးညိွ
မတက္ေစရန္ နီကယ္ရည္စိမ္ထားပါတယ္။
၅။ပါဝါျဖန္႔ေဝရာအပိုင္း(Outgoing Breakers)
Sub board ,MCC (motor control panel) ,DB (distribution board) တို႔ကို ပါဝါ ျဖန္႔ေဝ ေပးပါတယ္။
၆။ ကာပယ္စီတာဘဏ္႔ (Capacitor Bank)
ပါဝါ ဖက္တာ ကို ျမွင္႔တင္ရန္ အသံုးျပဳပါသည္။ ပါဝါဖက္တာအင္ပရုမန္႔တြင္ေလ႔လာႏိုင္ပါသည္။
