PISA: Unique System Protection Concept

Cost effective protection of 24V-branches.

The new PISA protection modules for the first time also protects the 24V supply voltage besides the output current of the connected loads. This feature is unique to PULS and unlike other commonly available protection modules on the market.

A safeguard circuit in the input stage of the PISA module works like a valve. It permits only so much current that the input voltage (corresponding to the power supply output voltage) does not drop below 21V
This ensures a safe and an uninterrupted supply voltage for sensitive loads even when they are connected to the same power supply as the PISA module.

Less critical loads that are not affected to short voltage interruptions or that could even be the cause of a fault on the 24V power supply are connected to one of the four current monitored and current limited output channels of the PISA module.

The PISA protection modules have one 24V-input and four output channels to which the current is distributed. The current on each output channel is electronically measured and switches off all outputs in case of an overload or fault.

If more than four output channels are needed, multiple PISA modules can be used on the same power supply. When the synchronization lines are connected on the individual units, the set of PISA units will then act like one single PISA module.

A PISA module with four output channels only requires 45mm width on the DIN-Rail. They are non sensitive to short peak loads and due to an active protection circuit, a false trigger of the protection elements even with loads that have a high inrush current or large input capacitance is avoided. 

The modules are clearly arranged and are self-explanatory to use. Integrating into machines and systems is very easy since there is virtually no risk of incorrect sizing or planning. There are also no issues when systems get modified, retrofitted or expanded. In many cases, it is even possible to use a smaller power supply since no additional current is needed which normally would be required to trip standard fuses. This can lower the application costs.

A relay contact reports as soon as the outputs have switched off and the module can be reset either with a local reset button or remotely by applying a voltage to a signal input.

PISA sets a new standard for cost. The cost for a PISA module is around half the cost of the standard market 4-channel electronic fuse module or is only slightly greater than the total costt of four traditional miniature circuit breakers with an auxiliary contact.

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