Industrial Environment
DC-DC Converters <40 W
6 Watt-Family
Edition 2/96 - Melcher AG
6 - 47
MELCHER
The Power Partners.
6.2
Installation Instructions
Isolation Tests
Input to output isolation voltage tests are performed as fac-
tory tests (100%) and should not be repeated in the field.
Melcher will not honour any guarantee/warranty claims re-
sulting from high voltage field tests.
Table 8: Isolation test voltage, coupling capacitance and
insulation resistance
Characteristics
Conditions
ICR
Unit
Uis io Isolation test voltage
AC: 50 Hz,
500
Vrms
Input to output
1 minute
1400
Vpp
DC: 1 second 1
700
V
DC: 1 second 2
800
Cio
Coupling capacitance typ
70
pF
Ris
Insulation resistance
at 100 V DC
≥1000 M
after 1 minute
1 For production test purposes in accordance with IEC 950/
EN 60950
2 Factory test procedure
Linear
regulator
Filter
Push-pull
converter
20
kHz
Vo
Go
Vi
Gi
Fig. 2
ICR 5/6, group 01 (single output)
Fig. 3
ICR 5/6, group 02 (dual output)
Block Diagrams
Linear
regulator
Linear
regulator
Filter
Push-pull
converter
20
kHz
+Vo
–Vo
Vi
Gi
Go
Connection in Series
If the outputs of one or more units are connected in series
each individual output should be protected by a zener diode
or preferably by a suppressor diode to avoid overvoltages
or reverse polarity at the individual outputs, e.g.:
– 1N5908 to protect 5 V outputs
– BZW04-11 to protect 12 V outputs
– BZW04-14 to protect 15 V outputs
(or equivalent types)
Such destructive voltages may occur at switch-on cycle of
the converters, if the output voltages do not rise at the same
time. The "slower" output(s) could be supplied and, as a
result, destroyed by the "faster" output(s) via the load. The
maximum output current is limited by the lowest current
limitation.
Connection in Parallel
Connection of the outputs of one or more units in parallel is
not permitted. The load distribution and the ripple values
could not be controlled.
Exception: .. ICR 5-05 (all 5 V single output units)
Cleaning
Two CFC free cleaning solvents have been tested and can
be recommended:
– Prozone from BP
– Zestron from Dr. O. K. Wack Chemie GmbH (Germany)
Unit 1
Unit 2
+
Uo
–
Uo
+Vo
Go
–Vo
+Vo
Go
–Vo
Submersion of the units in water for rinsing is permitted.
Drying should be done in the air.
Fig. 1
Outputs connected in series