086407-502 ABB Controller module motor card inventory

Description

The design of a system for protecting an electric network is of fundamental
importance both to ensure the correct economic and functional operation of
the installation as a whole and to reduce to a minimum any problem caused
by anomalous operating conditions and/or malfunctions.
The present analysis discusses the coordination between the different devices
dedicated to the protection of zones and specific components with a view to:
• guaranteeing safety for people and installation at all times;
• identifying and rapidly excluding only the zone affected by a problem, instead
of taking indiscriminate actions and thus reducing the energy available to the
rest of the network;
• containing the effects of a malfunction on other intact parts of the network
(voltage dips, loss of stability in the rotating machines);
• reducing the stress on components and damage in the affected zone;
• ensuring the continuity of the service with a good quality feeding voltage;
• guaranteeing an adequate back-up in the event of any malfunction of the
protective device responsible for opening the circuit;
• providing staff and management systems with the information they need to
restore the service as rapidly as possible and with a minimal disturbance to
the rest of the network;
• achieving a valid compromise between reliability, simplicity and cost
effectiveness.
To be more precise, a valid protection system must be able to:
• understand what has happened and where it has happened, discriminating
between situations that are anomalous but tolerable and faults within a given
zone of influence, avoiding unnecessary tripping and the consequent
unjustified disconnection of a sound part of the system;
• take action as rapidly as possible to contain damage (destruction, accelerated
ageing, …), safeguarding the continuity and stability of the power supply.
The most suitable solution derives from a compromise between these two
opposing needs-to identify precisely the fault and to act rapidly – and is defined
in function of which of these two requirements takes priority