An IDMT type over-current relay is used to protect a feeder through 5000/1 ACT. The relay has a PS of 125% and TMS = 0.3. Find the time of operation of the said relay if a fault current of 5,000 A flows through the feeder. Make use of the following characteristic. PSM Time for unity TMS (100% current = 1A) 2 10 3 5 8 10 6 4.5 3.2 3 15 2.5
Protection System
A system that protects electrical systems from faults by isolating the problematic part from the remainder of the system, preventing power from being cut from healthy elements, improving system dependability and efficiency is the protection system. Protection devices are the equipment that are utilized to implement the protection system.
Predictive Maintenance System
Predictive maintenance technologies are designed to assist in determining the state of in-service equipment so that maintenance can be scheduled. Predictive maintenance is the application of information; proactive maintenance approaches examine the condition of equipment and anticipate when it should maintain. The purpose of predictive maintenance is to forecast when equipment will fail (depending on a variety of parameters), then prevent the failure through routine and corrective maintenance.Condition monitoring is the continual monitoring of machines during process conditions to maintain optimal machine use, which is necessary for predictive maintenance. There are three types of condition monitoring: online, periodic, and remote. Finally, remote condition monitoring allows the equipment observed from a small place and data supplied for analysis.
Preventive Maintenance System
To maintain the equipment and materials on a regular basis in order to maintain those running conditions and reduce unnecessary shutdowns due to unexpected equipment failure is called Preventive Maintenance (PM).
We have an IDMT type over-current relay.
Given data,
CT ratio = 5000 / 1
Plug setting = 125 %
TMS = 0.3
Fault current (If) = 5000 A
The characteristics of PSM vs Time for TMS is given in the table.
We need to determine the time of operation for given relay and fault current.
So,
AS we know that,
Time of operation of relay = (time correspond to PSM ) * TMS
So,
We will need to first determine the value of PSM and corresponding time for that PSm from characteristics given in the table.
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