Honda CB160 Shop Manual page 98

94
5. ELECTRICAL PARTS
Fig. 5. 50 Silcon rectifier mounting section
'-----J-)
Fig. 5. 51
Connection
Items Selenium
Silicon
Terminal Voltage
l00V
aoov
/Cell
Direct Current
Less than 30V
150-250V
/Cell
Admittonce Tempe.
ratur.e
{ Contineous -10~+80°C -55~+175°C
Instant -20~+150°C
-55~+200°C
ro
times
r·5 times
Eddy Current
M /sec M" /sec
ax. 4 times
m. 1.5 times
/min /min
Efficiency
Max.
90%
Max. 99%
!Rectifier)
Voltage fluctuation
8~12%
2~3%
(Rectifier!
Fig. 5. 52 Comparison of silicon and selenium rectifiers
When current is applied to the silicon rectifying
~lement, due to the characteristics of voltage drop in
the positive direction, intense heat is generated at the
rectifying element section. As the rectrfying element
section is small and easily damaged by intense heat,
the rectifying element must be fitted tightly to the
cooling plate. Thus, protection in the form of heat
dissipation (due to the cooling plate! is provided.
(Refer to Fig.
5.
50)
There are two types of rectifying elements employed
in the silicon rectifiers, one of which has the P +
layer fitted on the upper surface of the cooling plate
(+element). The other has the N + layer also fitted
on the upper surface of the cooling plate ( - ele·
ment). These are coupled (Refer to Fig.
5. 51) and
employed in construction. (Refer to Fig. 5. 51)
I.
Feature comparison of silicon and selenium
rectifiers
( l )
As forward resistance is low and back resistance
is high, the front-to-back ratio is large. In the
selenium rectifier the ratio is 92% ond in the
silicon rectifier the ratio is 98.
(2) In the selenium rectifier employed in two-wheel
vehicles, weather resistance, especially moisture re·
sistonce, presents a problem. However, the silicon
rectifier· is not affected by moisture.
(3) In the range of permitted operational temperature
of selenium rectifiers, the maximum temperature of
the rectifier plate is 70°. In comparison, the tern·
perature range of the silicon rectifier is from
- 55°C to l 50°C. Especially at high temperatures,
this unit is suitable.
{4l As current in the back direction is low, self-dis-
charge of the battery, due to reverse current flow,
is aiso low {even when the vehicle is not in use). l
to l 0 ma of reverse current flow exhting in the
selenium rectifier is less than 0.1 mo in the silicon
rectifier. (Refer to Fig.
5.
52)