Helios SR250C User Manual page 2

Safety
The user is responsible for ensuring that input and output wiring segregation complies with local standards and that in
the use of the equipment, access is confined to operators and service personnel. A low resistance earth connection is
essential to ensure safety and additionally, satisfactory EMI suppression (see below).
HAZARDOUS VOLTAGES EXIST WITHIN A POWER SUPPLY ENCLOSURE AND ANY REPAIRS MUST
Electrical Strength Tests
Components within the power supply responsible for providing the safety barrier between input and output are construct-
ed to provide electrical isolation as required by the relevant standard. However EMI filtering components could be dam-
aged as result of excessively long high voltage tests between input, output and ground. Please contact our technicians
for advice regarding electric strength tests.
Earth Leakage
Where fitted, EMI suppression circuits cause earth leakage currents which may be to a maximum of 3.5mA.
Ventilation
High operating temperature is a major cause of power supply failures, for example, a 10
ture of a component will halve its expected life. Therefore always ensure that there is adequate ventilation for the
equipment. Batteries in particular suffer shortened lifetimes if subjected to high ambient temperatures.
Water / Dust
Every effort must be made in the installation to minimise the risk of ingress of water or dust. Water will almost always
cause instant failure. The effects of dust are slower in causing failure of electronic equipment but all electrical equip-
ment should be cleaned free of any dust accumulation at regular intervals.
Electromagnetic Interference (EMI)
Switching power supplies and converters inherently generate electrical noise. All wiring should be as short as practica-
ble and segregated from all equipment wiring which is sensitive to EMI. Residual noise can be reduced by looping DC
wiring through ferrite cores (sleeves). These are most effective as close to the power supply as possible and as many
turns of the wire taken through the core (+ and - in the same direction) as the core will accommodate.
External fuse protection
Fuses or circuit breakers must be used in all battery circuits to protect against short circuits. External fuses should be
used for power supplies/ chargers even though they are usually internally protected.
Connection polarity
It is critical to check the polarity carefully when connecting DC devices even with models which have non-destructive
reverse polarity protection.
Glossary of terms used in our user manuals
PSU = power supply unit
ELVD = electronic low voltage discon-
nect
SNMP = Simple Network Management
Protocol
Specifications are subject to change without notice. No liability accepted for errors or omissions.
BE CARRIED OUT BY A QUALIFIED SERVICEPERSON.
BCT = battery condition test
RPP = reverse polarity protection
LAN = local area network
o
C rise in the operating tempera-
ECB = electronic circuit breaker
EMI = electromagnetic interference
DOD = depth of discharge
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