Parallel and Series Connection

PST23 Rev. 04

Page 4 of 9

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A converter output can be connected in series with an output from a separate

converter, an external diode across each output is required. The maximum

output current of a serial-connected outputs is limited by the output with the

lowest current limit.Output voltages above 48V (SELV - Safety Extra Low

Voltage) require additional safety measures in order to comply with international

safety requirements.

Parrallel operation is possible with the addition of external diodes in series with

each output.

Redundant Systems Operation

When systems require a very high level of reliability and should work normally

in the event of a failure, N+1 redundancy is implemented where N is the number

of converter to support power requirement. If one converter fail, the remaining

ones still delivers the power to the loads.

The external diodes are required with the PST23 to ensure proper N+1

operation .

Hold-up time

The converter provides low hold-up time. If a hold-up time is required (some

railways applications for example) , use external input capacitors of adequat

size.

Formula for additional external input capacitor : C =2*Pout*th*100/(V²-Vi²)/n

whereas :

C

= external input capacitance [mF]

n

= efficiency [%]

= hold-up time [ms]

= minimum input voltage

V

= Input voltage level before interruption

Output Current Limitation

The converter output is continously protected against short-circuit by a constant

current limitation (no foldback). The short circuit protection is unlimited , the

operating area between nominal power and active protection area working in a

constant current mode may lead to power above nominal , then over stress of

the internal components.

Thermal Considerations

The converter is designed to be mounted on a dissipative area, in conduction

cooling mode.The max. operating temperature is the temperature of the base-

plate which should not exeed 100°C.

Addition of grease or thermal pad between the converter baseplate and the

chassis is mandatory .

Thermal protection

A temperature protection is integrated internally, disabling output when heatsink

temperature exceed 105°C . The converter automatically restart, when the

temperature drops below this limit.

Waveforms

Typical values for PST23110-24100

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Inrush current

Output noise