High current Power Supply 13.8V 40A

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more 13.8V power supply

Intro Detail :

SPECIFICATION

Â· Input voltage: 240

Â· Output voltage: 13.2V DC

Â· Output current: 40A DC

Â· Over current protection: current limiting al 40A

Â· Short circuit protection: Regulator shut off.

Â· Over voltage protection: Shuts off DC input and discharges input stage reservoir.

Â· Over temperature protection: Fan automatically operates as heat sink temperature of 65Â°C.

Â· Indicators: Power ON LED and Short circuit Protection active LED.

THIS PROJECT describes a Protected 13.2V 40A Power Supply Unit which, provided the heat sinking and cooling fan are suitable, is capable of running at full power at 100% duty cycle. It features soft starting, over voltage, current limiting, short circuit protection and automatic fan control. It is a substantial project that is not for the novice constructor.

CIRCUIT DESCRIPTION
THE HEAVY CURRENT carrying connections are shown in bold in Fig 1. The mains input passes through an EMC filter, protection fuse F1 and ON/OFF switch S 1 to transformer TI. The secondary output of TI is rectified by D I but cannot pass through open relay contacts RL1a. To start the PSU switch, S2 is operated allowing limited current to pass via R1 to slowly charge the reservoir capacitor C1. As C1 charges, the RL1 a pulls in closing the relay contacts and shorting out R1 and S2 placing the PSU in the ON state.

Voltage regulator IC1 is the popular 723. A 7.2V reference on IC 1:6 is fed to non-inverting ICI:5. This is compared with a sample of the PSU output voltage via RI3, RI4 and R15 to inverting input at ICI:4. The 723 can source 150mA at ICl:10, so transistor TR2 acts as a Darlington driver for the pass transistors TR3 to TR7 inclusive. Resistors R21 to R25 are current sharing resistors and the voltage across them is proportional to the current drawn by the PSU load.

When the current through R21reaches 8A (i.e. a total PSU current output of 40A) the voltage across R11 and R12 is 0.88V and is tapped from R I I to bias a transistor inside IC1 which robs IC1: 10 of some current, forcing the PSU into a current limiting mode.

Source Article:http://www.qsl.net/vu2upx/Projects/40apsu.htm
Thank you.

This entry was posted on Tuesday, August 21st, 2007 at 11:01 am and is filed under high current power supply, Power supply.

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