The list below is the possible applications for the STR Units. Click the appropriate button to get more details on the twelve applications.
3. Power Quality Monitoring
Each Option B DSTR Unit and Option B TSTR Unit samples the measured current and voltage waveforms ata sampling speed of 360 samples per cycle. Therefore, accurate values of total harmonic voltage and current distortion are available upon request from the Powernostics® Software.
The Powernostics® Software calculates the THDV and the THDI from the measured sampled data of the current and voltage waveforms.
- There are some loads connected to the power system which cause the generated sinusoidal current and voltage waveforms to become distorted. Electric arc furnaces, fluorescent lighting ballasts, and variable speed drives tend to be the most common causes of this distortion. This causes overheating of distribution transformers due to increased losses and thus increased fuel cost to generate power. Therefore, electric utilities have power quality (PQ) technicians who make measurements using portable PQ metering equipment at certain selected sites. The DSTR and TSTR Units along with the Powernostics® Software perform this function with a PQ Technician and can monitor multiple sites on a continuous basis.
- Some inverter based DR’s create harmonic distortion especially during low output conditions. IEEE 1547 has established THDV and THDI limits that cannot be exceeded at the point of common coupling (PCC). Also, the distribution system circuit may already have values at the PCC which are near these limits. Therefore, if a DR when inter-connected to the PCC, should exceed these limits of IEEE 1547, the DR must correct the problem, thus it is important to have measured the THDV and THDI, at the PCC before the DR is connected to avoid the extra cost to correct the problem.
- Because the Option B DSTR and Option B TSTR Units along with the Powernostics® Software already measure the THDV and the THDI values as a benefit of having the 256 samples per cycle data from the current and voltage waveforms, this information is provided at no additional cost.
- The THDV and THDI data obtained from the DSTR and TSTR Units may alleviate a DR not being able to interconnect at a potential PCC.