Relay Coordination Examples Excel
The unit protection schemes is based on – the sum of the currents entering an area of the system must be zero.Any deviation from this must indicate an abnormal current path. In these schemes, the effects of any disturbance or operating condition outside the area of interest are totally ignored and the protection must be designed to be stable above the maximum possible fault current that could flow through the protected area.2. Non unit type protectionThe non-unit schemes, while also intended to protect specific areas, have no fixed boundaries. As well as protecting their own designated areas, the protective zones can overlap into other areas. While this can be very beneficial for backup purposes, there can be a tendency for too great an area to be isolated if a fault is detected by different non unit schemes.The most simple of these schemes measures current and incorporates an inverse time characteristic into the protection operation to allow protection nearer to the fault to operate first.
2.1 Overcurrent protectionThis is the simplest of the ways to protect a line and therefore widely used.It owes its application from the fact that in the event of the current would increase to a value several times greater than maximum load current. It has a limitation that it can be applied only to simple and non costly equipments.2.2 Earth fault protectionThe general practice is to employ a set of two or three and a separate overcurrent relay for single line to ground fault. Overcurrent protection protects electrical power systems against excessive currents which are caused by short circuits, etc.
Overcurrent relays can be used to protect practically any power system elements, i.e. Transmission lines, transformers, generators, or motors.For feeder protection, there would be more than one overcurrent relay to protect different sections of the feeder. These overcurrent relays need to coordinate with each other such that the relay nearest fault operates first.Use time, current and a combination of both time and current are three ways to discriminate adjacent overcurrent relays.OverCurrent Relay gives protection against:Overcurrent includes short-circuit protection, and short circuits can be:. Phase faults. Earth faults.
The relay coordination and setting calculation for a case study substation is applied to clear faulty feeder. The simulation is done in ETAP software. Relay settings, coordination curves and settings table are discussed in detail. The excel sheet of the coordination settings also are attached. Type: PDF +.xlsx. What is Selective Coordination. To design a Selectively Coordinated system, the Engineer must choose pairs of overcurrent devices whose time current curves do no overlap in either the thermal range or the instantaneous range up to the current available at the downstream breaker. Example: A 20A branch breaker feeding egress lighting per 2005.
Winding faultsShort-circuit currents are generally several times (5 to 20) full load current. Hence fast fault clearance is always desirable on short circuits.Primary requirement of Overcurrent protectionThe protection should not operate for starting currents, permissible overcurrent, current surges. To achieve this, the time delay is provided ( in case of inverse relays). If the interrupting rating is not properly selected, a serious hazard for equipment and personnel will exist.Current limiting can be considered as another overcurrent protective device rating, although not all overcurrent protective devices are required to have this characteristicVoltage Rating: The voltage rating of the overcurrent protective device must be at least equal to or greater than the circuit voltage.
Inverse Time relays are also referred to as Inverse Definite Minimum Time (IDMT) relay. Inverse Definite Minimum Time (IDMT)The operating time of an overcurrent relay can be moved up (made slower) by adjusting the ‘ time dial setting’. It’s used when Fault Current is dependent on generation of fault not fault location.Normal inverse time Overcurrent Relay is relatively small change in time per unit of change of current.Application:Most frequently used in utility and industrial circuits.
'Most of the ‘relay’ problems I have faced were actually human errors instead of equipment errors. Most relay tests would not catch these errors. Examples: Wrong CT/PT ratios, wrong polarity.This course helped show how testing a relay can also catch human errors in the installation of equipment or wiring and the programming.This course is unlike any I have ever seen. I have paid ten times the cost to attend training in person, and the training usually covers mostly theory and standards. This course actually shows you how to do real-world relay testing.' I n this seminar, you’ll get to look over my shoulder as I test a relay from start to finish, using everything I've learned from over 20 years of relay testing.You’ll learn the basic skills you need to test any digital relay with any modern test-set, how to perform each testing step, and why each step is important.I’ll show you how to make smarter test plans that are quicker and more effective than traditional methods (including tips and tricks you won’t find in any manual or YouTube video).Once registered, you'll get unlimited access to.
You can get a certificate of completion after:. Passing the final quiz with a score of 80% or higher in a online training course.
Marking all topics and lessons as completed as you watch the videos in our online training seminar seriesYou can submit your certificate to the regulator to request credit for the course. All of our training programs are pre-approved for NETA CTDs. Simply add the title of the course and a copy of your certificate to your application for credit.We can help get pre-approval for courses. Contact and we will do what we can to get our courses approved with your agency. Our online training material is specifically designed to be self-paced, and you have access at any time 24/7/365.If life gets in the way, or you prefer to take it one small chunk at a time, no problem.
Relay Coordination Examples Excel Chart
Just set it down, and pick back up when it's convenient for you.That's the beauty of online training. You can't pause an instructor in a classroom, or someone walking you through steps on the job. But you can pause our videos, take notes, implement what you've learned, and come back right where you left off. Life would be perfect if our bosses and companies knew exactly what we needed and provided it to us at just the right time.
But, like it or not, things don't tend to work out that way most of the time.What you can do though, is take your career into your own hands, learn the fundamentals, and excel at your craft. Once you do that, you become indispensable to your boss, clients, and the industry at large.Our online training programs are designed to be convenient, affordable, and exactly what you need to learn on your own, despite what is or isn't offered to you by your organization.