Specifications are subject to change without notice. No liability accepted for errors or omissions.
11
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
BE CARRIED OUT BY A QUALIFIED SERVICEPERSON.
Electrical Strength Tests
Components within the power supply responsible for providing the safety barrier between input and output are con-
structed to provide electrical isolation as required by the relevant standard. However EMI filtering components could be
damaged as result of excessively long high voltage tests between input, output and ground. Please contact our techni-
cians for advice regarding electric strength tests.
Earth Leakage
The EMI suppression circuits causes earth leakage currents which may be to the maximum allowable of 3.5mA.
Ventilation
High operating temperature is a major cause of power supply failures, for example it has been well documented that a
10
o
C rise in the operating temperature of a component will halve its expected life. Therefore always ensure that there is
adequate ventilation for the equipment. Batteries and cooling fans also suffer shortened lifetimes if subjected to high
ambient temperatures - both should be included in a routine maintenance schedule to check for signs of reduced effi-
ciency.
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. This is particularly important where internal
fans are fitted.
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 cable 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.
Fuse ratings
Check that the wiring and fuses or MCBs match the rating of the PSU or converter. Adequate fuse protection of battery
circuits is very important owing to the large potential currents available from batteries.
Connection polarity
It is critical to check the polarity carefully when connecting DC power supplies and chargers to equipment. Boost
chargers and some float chargers usuall have reverse polarity protection (RPP), which can be electronic (non-
destructive) or by an internal fuse which needs to be replaced if a battery is connected in reverse.
PSU
= power supply unit
BCT
= battery condition test
ECB
= electronic circuit breaker
ELVD
= electronic low voltage disconnect
RPP
= reverse polarity protection
EMI
= electromagnetic interference
Glossary of terms used in our user manuals
SNMP
= Simple Network Management
Protocol
LAN
= local area network
DOD
= depth of discharge
