Protective Device Messages

Protective Device Pickup Messages

"Fuse Picked Up On Over Current."

"LV Breaker Picked Up On Over Current."

"Relay Picked Up On Over Current."

"ATS Picked Up On Under-Voltage."

"Contactor Picked Up."

“Relay Picked Up On Under-Frequency – XX Hz”

Description – Protective devices (PD) modeled by you can be globally enabled during the simulation. These devices are then monitoring current, and if their device curve is satisfied (current meets or exceeds the fuse max-clear curve, LV Breaker max-clear curve or relay pickup current), then it will trigger a pickup message. This is an informational message only, and in most cases does not signify an error or warning condition.

Note: If protective devices are picking up which should not be doing so, we suggest a thorough review of the protective device settings through their TCC plots.

Protective Device Reset Messages

"Fuse Reset at I Squared T = XX%"

"LV Breaker Reset."

"Relay Reset at XX% Travel. Now Traveling Back."

"ATS Reset."

"Contactor Reset."

“Relay Reset. Timer Reset.”

Description – If a protective device has already picked up (see just above), but then the current drops below the trip point (below the fuse max-clear curve, LV Breaker max-clear curve or relay pickup current), then the protective device will reset. This is an informational message only, and in most cases does not signify an error or warning condition.

Note: If protective devices are re-setting that should not be, we suggest a thorough review of the protective device settings through their TCC plots. Also note that for a fuse reset (which really is not a physical reset, but an energy condition where the fuse element did not melt), the fuses exposed I Squared T in percent of fuse capability is displayed in the Message Log. This then gives an indication of fuse fatigue. Note that the fuse model never resets the accumulated energy in a single simulation. This then means that fuse pre-heating can be simulated for several contingency events (where the fuse may blow faster on the second event due to energy already accumulated). This modeling method was implemented based on the assumption that most dynamic simulations run to about 20 or 50 seconds, and that this would not be enough time to significantly dissipate heat accumulated in the fuse.

Protective Device Trip Messages

"Fuse Tripped On Over Current."

"LV Breaker Tripped On Over Current."

"Relay Tripped On Over Current."

"ATS Tripped On Under-Voltage - Waiting for Transfer."

"Device Tripped on Relay action."

“Relay Tripped on Under-Frequency – XX% Hz”

“Device Tripped by Under-Frequency Relay.”

Description – If a protective device has picked up (see just above), and it then satisfies the device’s trip point (the fuse max-clear curve, LV Breaker max-clear curve or relay TCC curve), a message is generated to note that the device has tripped. For a Fuse and LV Breaker, an additional signal is then sent to the switch or breaker modeled in the network to force the device to open. For a relay, we now start a one-way timer (which cannot reset) that will, at a later time, issue a breaker trip signal. This is an informational message only, and in most cases does not signify an error or warning condition.

Note: If protective devices are tripping that should not be, we suggest a thorough review of the protective device settings through their TCC plots.

More Information

Dynamic Stability
Messaging