Hitachi H20-T Technical Notes page 53

Reset it .
Set t h e cu rr en t va lu e wit h loa d cu r ren t , or repla ce
t h er m a l over loa d rela y.
Repla ce t h er m a l over loa d r elay, a n d mor eover, u se
pr ot ect ive box su it a ble for en viron m en t .
Repla ce t h er m a l over loa d r elay.
Rem ove t h e ca u se a n d r epla ce t h er m a l overloa d
r ela y. Th er m a l over loa d rela y dose n ot prot ect
la r ge cu r ren t like sh or t cir cu it .
Ch eck t h e cir cu it a n d m a t ch it wit h con n ect ion
dia gr a m . Con cu r r en t ly, check gr ou n ding a n d dis-
con n ect ion of cir cu it, or t igh t en in g of con nect ion
t er m in a ls.
Con n ect it t o mot or ter m in a ls or loa d t erm in a ls of
st a r t er. (see pa ge 47)
Repa ir or r epla ce t h e oper a t in g swit ch . (pu sh -
bu t t on swit ch , floa t -fr ee swit ch , lim it swit ch , et c.)
Ch eck t h e lim it swit ch , pr essu r e swit ch , et c.
Repla ce pa r t s. (coil)
Cor r ect ly mou n t it t o t h e ver t ica l fa ce (see pa ge 36)
Select t h e su it a ble st a r t er.
Re-exa m in e t h e a pplica t ion . In ca se of plu ggin g a n d
in ch in g, it is n ecessa r y t o lim it t h e r a t ed ca pa cit y.
Use on e wit h pr ot ect ive st r u ct u r e su it a ble for
en vir on men t .
Rem ove t h e ca u se a n d pr ovide a relia ble, pr ot ect ive
device a ga in st sh or t cir cu it .
Ch a n ge it t o a cor rect wir in g.
Repla ce coil or ch a n ge t h e con n ect ion of wire for
coil t a p.
Ch a n ge t o t h er m a l over loa d r ela y wit h sa t u r a t ion
r ea ct or ; t h er e is a n ot h er m et h od t o u se t im er.
(see pa ge 31)
E xa m in e a n d ch a n ge t h e m ou n t in g met h od a n d
pla ce of st a r t er.
Ch eck t h e cir cu it a n d m a t ch it wit h t h e con n ect ion
dia gr a m . At t h e sa m e t im e, ch eck t h e gr ou n din g
a n d discon n ect ion of cir cu it a n d t igh t enin g of
con n ect ion ter m in a ls.
Con su lt wit h ou r com pa n y's a gen t , sa les st or e a n d
ser vice st a t ion a bou t t h e t r ou bles, a n d ch a n ge t h e
in st a lla t ion pla ce of t h er m a l over loa d r ela y or
r epla ce it wit h on e wit h a ppropr ia t e ch a r a ct er ist ics.
Ta kin g in t o con sider a t ion t h e sequ en ce of over loa d →
oper a t ion of t h er m a l over loa d r ela y → in ca pa bilit y of
closin g, in vest iga t e t h e ca u se a n d r em ove it , t h en
r eset t h e rela y.
E lim in a t e t h e ca u se a n d in st a ll a pr ot ect ive device
a ga in st sh or t cir cu it , for in st a n ce, fu se-fr ee br ea ker
a n d t h e like.
Th er m a l over loa d r ela y
oper a t es.
Miss -select ion of t h er m a l
over loa d r ela y cu r r en t
Cor r osion of h ea t er du e to
oxida t ion
Oper a t in g fa ilu r e of t h er m a l
over loa d r ela y
F u sin g of h ea t er
Wir in g fa ilu r e of oper a t in g
cir cu it
In st a llin g m et h od of power
con den ser
Bou n ce of oper a t in g swit ch
Oper a t in g a n d con t a ct fa ilu r e
of oper a t in g swit ch
Miss -a pplica t ion of oper a t in g
cir cu it volt a ge
E r r or in mou n t in g con dit ion
Miss -select ion of ca pa cit y
Oper a t in g (open /close)
fr equ en cy is t oo h igh .
Miss -select ion of pr otect ive
st r u ct u r e fr om du st or ga s.
Sh or t cir cuit or gr ou n din g
of t h e loa d side
Miss -con n ect ion for rever sible
t ype
Miss -con n ect ion of wir e for
coil t a p
Th e st a r t in g t im e of loa d is
lon g.
Vibr a t ion a n d sh ock a r e gr ea t .
Wir in g fa ilu r e
Am bien t t em per a t u r e is t oo
h igh .
Am bien t t em per a t u r e is t oo
low .
Over loa d of m a ch ine
sh or t cir cu it t r ou ble of
wir in g