We were trying to capture capacitor switching transients on 4 kV metal-clad switchgear using an Electro Industries Nexus 1500 meter. With the transient voltage trigger set at 175% of nominal, we got a large number of transients before we were able to switch the capacitors. There were so many of these transients that the transient log file filled up in about 10 minutes. There were multiple voltage spikes of very short duration occurring at the peaks of Phase A voltage and sometimes on Phase B. See the attached waveform.
Have any of you experienced such voltage spikes? Any idea what would cause them? The transients do not appear to cause any operational problems. The switchgear serves a 3000 HP motor without a VFD, another 3000 HP motor with a Rockwell PF7000 VFD, and two 4 kV - 480 volt transformers. The 480 volt load includes motors, some with PWM drives and some motors without VFDs. Measurement was made through 2400-120 volt VTs.
Could these spikes be a measurement anomaly? The width of the spikes is such that they may only be one sample wide at 1024 samples per cycle.
Have any of you experienced such voltage spikes? Any idea what would cause them? The transients do not appear to cause any operational problems. The switchgear serves a 3000 HP motor without a VFD, another 3000 HP motor with a Rockwell PF7000 VFD, and two 4 kV - 480 volt transformers. The 480 volt load includes motors, some with PWM drives and some motors without VFDs. Measurement was made through 2400-120 volt VTs.
Could these spikes be a measurement anomaly? The width of the spikes is such that they may only be one sample wide at 1024 samples per cycle.