110 An

.ry tle.iLd

Sfli..,

Larter wa8hing machines ope.ate fioh the +pha6e a.c. powe supply wilh . lphce induction motd drive. Control iteos in a walhine mchine include water ldel switches,t-mDdatuJe 6witcheslbimetalic) md solmoid valves in the iilt dal @ilet water lins. Ud and door s*itches intempt lhe dain power supply il.oPerated after the wasrun8 sequ6e M3 Detutr. Spin dlyeB have a sfety d@! intedock thar prev4ts it beiry opemd while the drm i! stil solving. Tunble dry4 often oily have one mtor with a double ended dhaft Io! dium dd blowd fan Lint anal ftiff colecte on the dotor and wtrinc which c6$3 no trouble while it r;mains dry and in snall qtrtities. Pdiodjc Eibvat of tle flu-ff will help prevent fautts disins where _m.v danm;r mbin. with ihe flutf to duse condu.tive trackine btween live conductors and to arith. Stull single-phare notors are rometimes Dstected bv a thmal ot{ut 5ttached

5.10. Cathodic Plotection

The outer surfac of a shiDt hlll i! subidted to electro-chemi@I attack bv .or;osive .ffients that flow betwedl des of the hul which de at rliehdv diffdnt el*tric poientials. Di$iail,r metdb, vdiatioE in shuctual and chemcar qifomity in htdl plates md weldin& diffanc$ in paint thiclqe6s md qualjty, water tempdat(e, salinity od atation aU .ombine to cau* de6 of thE huI to beone eithd arodri:(positive) or o&odi' (nesative)Iis. 5.21 ebows ihat in the hul, elecforu Odw fton anode to .athode lavin? positivelv chatsed ilon ions at th; :uodic aia. Ai i-he dthode the etre.t of the dival of elecEoE is to produce negatively charged hydrcxyl id,s (ol4 bv electolvsis of lhe 66 watd. These niatiE i;c flow throqh the 6ea to th ano.lic area where thy coobine

io the statd endwindincs.

Fi9, 5.21 ca6o.th pFElirc rdio,

with tne poditive_ irc.n-ioN_to_ form be(un),. rm Fnous hydronde j! fu.ther oxidisedby djssolved oxygen ro foq feric hy.lroxide le(OH)J whi.h is nsi. Thtrs th. anodi. ,rea is Fadualy conoded away whnst no corosjon tales plae at $e caihodic,rea.

Ihis natulally .orosive action can le overcome if the complete hull is mad cathodic,i.e, electronsare allowed ro eive at the hull surface and oroduce ;esative hydrcxyl io6 but no elecEons zhc el4-trcde (450nV nrga,@ro hull) leave the huU to prodrce positive ircn Snverelft]Iode (600nv p6i,iu to hull) ios, This G achievedby fitting jnsulated lead or pl.tinised titaniuh anodes to When satufactorily protected, the prothe hull .nd applying a posiriv d.c. tection (]Denr wil hake the hul! 200mV to them with respect ro rhe more neEative, i.e. a zinc reference Potenrial -wiU e]{Eode register 250mV negativeto h'nl and silvs 800 mV positiw to hull Tle ne8ativelychar8ed hydroxyl io.s as shown in FiE- 5.22. The lefelence (OH) now Dassto lle insulated lead eleckode voltaSe may/ threfore, le anodes c.usinE the lead slrface ro used to monitor the lroiection, bur change1o lead peionde PbOr. more imponaft, io Ned ad the si$al The potential is of slch a value that source to automatically leEulate the it jlst de..omes the oriSinal corcsion vadueof protection (xjl@t. .Eent md gives nse to an imPEsed Cathodic protection systems fiited in Protection c6ent which flows in the .ompleb cncuit. The value of Drotection ships consist of a nmber of anodes0ead .trrent must be diticalty .oiitroled io d platinised titanium) fitted to the hul at selectedplded !low the waterline, 6d ist prevent conosion, as beyond this vdue the in@ase in the rate of rlease .onhol equipment which automatically of hydrotyl ions wnl causesDonEhess regulates the anode culleni to the md naking of the and-fouling pain1. requifd value.Diieci ffint is suppued tothe anodes,afts transfom.tio; dd Initialy the eletlo\^ic .aclion will fom rectilEatioa f!6 the ship's 440 V 60 Hz Iead peroride (Pbor'on the surfa. 3-phasea,c, distribuiion system, The of the anodes and whn this skin is control equipment compris$ ref@nce foned the action reduces, The anodes electrcdes.d dDufier assemblvand one r.ke on a rich broM appedance (positive or mde hansforiier re.titier u;ih

lead-acid battery plate) and in seftice @ expectedto lsst 7-10 yed. The cmect value of plot*tion .unent can be detemined by refercn.e electiodes. These de either of zinc d silver attached to the hull, but insulated hom it, below the watedine. The voltase measuredbetween the hull and re-ferenceelechoded of an unpiot*ted ship with sea water d n

rttl
d

Ii8 5 22 PDredionvolr:gs,

1,12 Anolbry 6ledic,l SePi(e6

Poy_el:'tpt

basic.r4u raranggnon(sfor6rhod/c pbred,on

Fi3 t.zl stup:nod6 dd dpEsd tunr .onfrot3ynm.

The anode cuent control is usuallv regdaied by ele.tronic thFistor coiitroUersand the diaslam in lia 5.23 oudines a tlpical schde. The .odtlol equipment automaticallv monitors the siie of anode clrrerir .equired whi.h wil vary with the ship's sreed, waler tehoeraturedd salinitv cbndirion paintio* erc.Tvpical or doi; tuent denaities rdse fro;io @{/m? to 40 mA/m, for the p;otction of painied idaces md 100 to 150 mA/m: for b,'e Ihe total impre$ed drrcnt for a hul in good condition nay be as low as 20 A, Mdimum conholleroutpursmy' be uD _ toabout600AaiSV Cathodjcprctec+ion does nor appear to determouuscrlar Fowth on the;inps

hul so a to? coator anti foul (poisono6) P.ni 6 sru ne.s6ary. Typical referenceand main dode ourlines are shown in FiE. 5.24. Monito.ing fa.ilities in the .athodic protection conhol cabinet may provide . Refrence electlode voltase (hull potential) ' Aiplifier output voltage . Total anode ffient . Individual dode cuent Metruenents should b reEU lady loEEed to8eher w'tn tne shrp operatinScondition8, e,8 location, dJaught, warer

lead'a sripsmounEd a in oy grass fibredsuraiinq mdrding

IiB 5 24 Retmncdd min anode(onsd(hon ourlrs.

tempe.ature, etc. chanses in undeMater huli area, speed, waier tehpenture/ salinity and paint condjtion will all caNe the anode cunents to vary, The -hull potential should, however, iemain constant a Droredvresulated in svstem, elthoush ir,e reiereiceelecirodes . n d t h e d o n i t o r i n s r . c r l r t i e ss i v e a reasonable <lav to d:av check rh;v a.e only deasuri;g h rh; vicinity o'f the When the ship is moord sinSly or stoplEd at sea voltaeeleadinsscan be tara; berweena po;ble s v; or zinc test electrode and the shiD's hu]l. This podable eleckode is lowe.ad 2-3 nehes below the water sulace and as dose as possible to the hull at specjfied positions around the ship. : Check the ;andacturer's instruciions regddin8,tne sbrage_and kftin up of tne Portabre rectlode. e be imersed in a plastic buckei of sea water lor abolt 4 hours before rhe hdl test. With the cathodic protection switched on and working nomaly, the voltage measuredbetween hull and a snver/silver chbnde portable elect ode should be 750 850 ;V using a high resistance multimeter(e.e. analode or digrtalt}?el the electrode"bing p"ositire Wnen dly docked, ensure that the nain anodes and referenceele.trodes de covsed with paper rale to prevent

To ensure that the rudder, Dropeller smw and stabiliser re.eive-rne'same fins degte of cathodic proiection as the hull it is necessary ro elednca\y eqnh-bond these items to tne hul. The rudder sto& may be bonded by a wire braid linLing the top of the stock to the deckhead dnecdy aboveit. Carbon brushesrulbins on the .otating nain ?ropulsion shalt effectively bond the shaft to the hrillA periodic inspe(tionof suci earihinq is worrnwnne the hrusne5 is we.r awat dd m6y occasionallystick in then brush holders.

5.11.BatterySupplies
A propedy maintained storage battery wil instantly supplyel*tric powerlien required.This featu@oa*es a lattery the tey element in the provision of essential_ edergenca and pdwer suppus Essential routinepower supplies. .9. fo! r.dio eqdpdent. telephone e.change, general fir detection, alam (ujts etc., are ofien sulplied ftom two sets of battdies worked on a regtlar charEe/ Eme.Sencybattery supplies, e.E. for energency Eeneralor srart-uP and eme.gencylighting, de sed in a sl,r!|ry