1
POWER SUPPLIES SPS1000 SERIES
CIRCUIT DESCRIPTION AND OPERATING MANUAL
CIRCUIT DESCRIPTION
Power Supplies SPS 1000 series are based on the primary switched AC/DC converters topology.
Power supplies of this technology have got a high efficiency factor. Simplified functional diagram is
shown in the fig.1.
The 230 AC line voltage is rectified by a bridge rectifier „U
1
“ and smoothed by a large electrolytic
capacitor „C
f1
“. RFI filters „F
1
“ protect the line and a load from a high frequency interference
produced inside the power supply. When the unit is switched on, the electrolytic capacitor is charged
via NTC resistors. Inrush current is limited approximately to 60A/10ms. This must be taken into
account at a fusing of the line outlet. It is recommended to use 16A normal fuse or 10A slow one. The
rectified 230V AC (300V DC) is chopped by the inverter „S“ which consists of four MOSFET
transistors and transformed to a lower voltage. The 50kHz power converter is of full bridge type. The
regulation of the output voltage (current) is achieved by pulse-width modulation varying duty cycle
(D=0
÷
80%) at the constant frequency.
F1
S
U
F2
2
U
1
t
NTC
NTC
t
C
f1
C
f2
TL
L
N
P E
U1
N1
S W ITCH
-
+
PH
+N
+P
E~
50
Hz
,2
30
V/
TN
-S
ZJ
U2
I2
RO
M
M
ROV
RS 232
"OUTP UT"
U
I
ž
ž
RE
M
O
TE
Um
I m
m
I
Um
Už
ž
I
"OFF"
"ON"
+5V
"OFF"
"ON"
+5V
0-5V
0-5V
TR
Input
filter
Input
rect.
Inverter
Output
rect.
Output
filter
P TC1
P TC2
Fans
speed
control
:
:
Control
circuit
Display unit
Fig.1
Option
Lo
ca
l
Sw
itc
h
(Disable)
S witch
