8 | SAMLEX AMERICA INC.
SeCtIOn 3 |
Description & Principle of Operation
Switch for over temperature shut down will open and will activate over-temperature
protection circuit to shut down the Power Supply Section. When the windings cool
down to temperature ≤ 75°C ± 5°C / 167°f ± 9°f, the switch will close, shut down circuit
will be de-activated and the output power from the Power Supply Section will be
restored automatically. During the time the Power Supply Section is shut down due to
over temperature, the backup battery will supply the load and will start discharging.
When the Power Supply Section cools down and resets, it will once again start supplying
the load and re-charge the battery.
!
cAUtion!
The fan sucks cool air from the vent openings on the sides of the unit and discharges
hot air through vent openings at the bottom of the unit. PLeASe enSURe tHAt tHeSe
Vent oPeninGS ARe not oBStRUcteD.
NoTE: Please refer to fig 2.1, page 5 and explanation under heading “Principle of
operation”, page 7.
oVeR LoAD / SHoRt ciRcUit cURRent PRotection
Battery Backup Function is not Used - external Battery is not connected and
the Unit is Used as a Power Supply
In this case, the entire load current will be supplied by the Power Supply Section and will
be limited to a maximum of 25A by its Current Limit Circuitry. If the load tries to draw a
higher current than the current limit value of 25A, the output voltage at the Load Ter-
minals (3, 4) and the Battery Terminals (5, 6) will not be regulated and will drop below
13.8V± 0.2V. If the load impedance is further reduced, the current will remain limited at
25A but the voltage will drop further. In case of short circuit, maximum limited current
of 25A will continue to be supplied into the short circuit but the voltage will drop to
< 2V in case of a near dead short (Load impedance will be very low – say < 100 milli
ohm). If over-load / short-circuit current of 25A continues over prolonged period
(> 100 sec), the external 25A load side fuse (f2) will blow and will disconnect the load. If
the overload / short circuit is removed before the external 25A load side fuse (f2) blows,
the output voltage at the Load / Battery Terminals will automatically recover when the
load current drops to less than 25A.
Battery Backup Function is Used - external Battery is connected
If the load tries to draw current higher than the current limit value of 25A of the Power
Supply Section, the output voltage of the Power Supply Section will not be regulated
and the voltage at the Load Terminals (3, 4) will drop. Portion of overload current
beyond 25A will now be fed from the battery and the battery will start draining at this
differential current. for example, if the overload current was 40A, the Power Supply
SeCtIOn 4 |
Protections
