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USER GUIDE – REF. PSF 243
POWER SUPPLY/CHARGER – 24V DC 3 AMP UNIT
General
This power supply unit is for powering a 24V DC 3amp load (2.5 amp load + 0.5 amp charge). It also incorporates a 24V
DC charger for use with Sealed Lead Acid Batteries up to 12ah. If the unit is being used to supply a load and charge
batteries, the total load should not exceed 3 amps. If the unit is being used to supply a load only, without standby
batteries, it is necessary to fit a resistor (value 10k ohm) ac ross the batte ry term inal b loc k i nstead of the battery leads to
illuminate the charge fault LED. The uni t should be fitted in an upr ight position on a solid surface using the fixing holes provided.
Supply
Supply to the unit should be 240V ac 50Hz with ear th fed to the unit via a 5amp fused outlet fitted adjacent to
the unit. The mains supply in the enclosure should be wired into the fused terminal block next to the PCB. The
unit should be earthed.
PCB CONNECTIONS
Lid Indicators
Green = Supply Healthy Amber = Fault
When the Gree n light on l y i s illuminated, the unit is opera ting normally with supply to th e load and the batteries
(when fitted) are receiving cha rge curre nt. When the Amber light is illuminate d at the same time as th e Green
light there is a fault on either or both of the output supply and the charge supply. If the Green light is NOT
illuminated, the mains supply is not present or the main “overload” fuse has blown.
PCB Fuses
F.1. Battery = 3Amp quick blow F.2. = 3Amp quick blow
PCB Indicators
Amber (upper) = Short circuit fault/supply fault.
Amber (lower) = Charge output fault.
Upper indicator illumina ted, is caused by eithe r a short circuit in the wiring, or an excessive load.
Lower indicator illuminated is caused by a blown fuse (bottom) in the bat tery charge output (i.e. Short circuit of
the ba ttery leads) or by output supply sho rt circu i t . It is essential the battery is not fitted “ REVERSE
POLAR ITY” as this will cause damage to the charging circ uit which may be i rrep arab le.
Battery Connections
The typical batt ery ty pes to be used are Yuasa NP12-7. Two of these in equal state of charge are req uired to
make up 24V. The supplied leads should be used.
The batteries can be charged faster by fitting the jump er link J5 (on circ uit board CUS-256B). This increases
the cha r ge rate by 50%, bu t because of the 3A total power limit, care should be taken to ensure that the load
does not exceed 2A con t i nuo u s.
Battery Cut-Out
During A.C. fa ilure the system will switch to battery standby, the output voltage level will follow that of the
batter ies down to approximately 19V. At this poi nt the cut-out circu it for le ad-aci d ba ttery pr otection will
discon n ec t p owe r a lt oge t he r . (ci rc u i t bo a rd CU S-256B 2006). Sho ul d A.C . no t b e ava il a b le whe n t est in g wit h
he alth y b at t eries, a temp ora ry sh or t o n J 11 (bo ar d CU S-256B) will act iv ate the ba tt ery cu t - in t o p ower t h e lo a d .
(if there is sufficient charge in th e batt eries)
Fault Relay Option
The fault relay output will go from norm al to fault state when A.C. power is removed or when there 's a fault in
the uni t as indicate d by LP2. Sometimes a fault condition may show up if there a re t empo ra r y excesses in the
total load or if there's a dip in the mains sup ply. It is advised tha t t he load cirui t be divided and a lar ge r power
sup p ly/ch ar ge r i ns t a lled if this situa tio n p ersis ts.
J3 J4
J9 J10
J13
A.C. FROM
TRANSFORMER
DOC-005J
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