Determining magnitude, phase, and frequency thresholds by pulse ramping definitions
With Pulse Ramping, quick, accurate and thorough determination of pick-up values of multifunctional relays is easily done. Pulse Ramping allows for testing a protection element pick-up value without disabling associated functions. This eliminates a potential source of error. The use of Pulse Ramping also avoids high continuous testing current for electromechanical relays with high instantaneous settings.
Pick-up testing of:
- multifunctional relays with overlapping elements
- overcurrent relays with multiple elements
- generator and motor protection
- rate of change relays (including df/dt)
Application example Overcurrent
Often overcurrent protection is realized with two stages; a standard stage with a longer tripping time and a high set stage with a very short trip time. With Pulse Ramping, a test of the pick-up value of the high set stage can be done easily: the pulse length is set shorter than the standard stage tripping time and so pulse ramps do not force a trip of this stage.