APPLICATIONS

The list below is the possible applications for the STR Units. Click the appropriate button to get more details on the twelve applications.

DSTR & TSTR monitoring Units

Some of the applications use the DSTR Unit on distribution circuits and other applications use the TSTR Unit on a transmission line. The table below summarizes the applications of a STR Unit.

	Application	Description
1	Weather Station	The Basic STR Units incorporate a weather station feature which measure the ambient temperature, solar radiation, humidity, barometric pressure and lightning stroke current. In addition to the foregoing measured data, Option A Units measure rainfall, and Option B Units measure the line voltage and lightning stroke voltage. The Powernostics® software calculates the effective wind velocity. All STR Units incorporate a novel patented method of measuring the effective wind speed (normal to the conductor)from 0.5 mi/h up to 135 mi/h. The traditional mechanical anemometers inherently have inertia which prevent them from accurately measuring low wind speeds and high wind speeds and can freeze up during sleeting rain conditions.
2	Power Quantities Monitoring	The Basic DSTR Units measure the line current from 6.8 amperes (with LTPS) and up to 1000 amperes of steady state true RMS current. Option B DSTR Units measure, in addition to the line current, the line to line voltage or the line to neutral voltage of delta connected or wye connected distribution systems, respectively. Option B Units measure line voltage, line current, power factor, kW, kVAr, and kVa up to 34.5kV. The Basic TSTR Units measure line currents from 26 amperes (with LTPS) to 2500 amperes of steady state true RMS current. The Option B TSTR Units measure both line current and line to neutral or line to line system voltages up to 345kV, although these Units are designed to operate up to 500kV. The Option B Units measure line voltage, line current, power factor, MW, MVAr, and MVA.
3	Power Quality Monitoring	Each Option B DSTR Unit and Option B TSTR Unit samples the measured current and voltage waveforms at a 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 Unit sampled data of the current and voltage waveforms.
4	Lightning Characteristic Data and Waveforms	The Basic STR’s measure the actual lightning stroke positive or negative peak current value and waveforms and Option B Units measure the lightning stroke voltage and current waveforms. The Powernostics® Software shows the actual waveforms of lightning current and voltage and their peak current and voltage values.
5	Fault Data & Waveforms	The Basic STR Units among other parameters measure the fault current and record the waveforms. The Option B STR Units among other parameters measure the fault voltage and record the waveforms.
6	Real Time Thermal Rating	The Basic STR Units measure the ambient temperature, solar radiation, conductor temperature, and line current. Also, the Option A Units measure the line sag. According to the heat balance equation under steady state conditions, (I²R) plus the solar radiation received from the sun (Q_s) must be equal to the heat lost by thermal radiation (Q_r) and convection (Q_c),or I²R+Q_s = Q_r+ Q_c. (1) Since the STR Unit measures the line current (I) and conductor temperature (tc) of the line, then the (I²R) term is known. Also, the Unit measures the ambient and conductor temperatures, therefore the term Q_r is a known quantity. In addition, the Unit measures the total solar radiation Q_s, and as a result Q_c can then be found directly from equation (1). Furthermore, the surface coefficient of heat transfer h can be determined from Q_c, since t_c and t_a are known quantities. It follows that all the values of the terms in equation (1) are obtained directly from the mesured values which describe the existing thermal state of the conductor. From this, as shown in Figure 11, the real time value of the current in equation (1) can be found from I _max = ((Q_r+ Q_c – Q_s)/R)^½ (2)
7	Line Sags	Option A Distribution STR Units among other parameters measure the sag of the line. Option A Transmission STR Units measure line sag,tower tilt, broken conductor, insulator/line swing angle and conductor vibration. In addition to line sag, Option A Units include the measurement of the conductor temperature, ambient temperature and line current. Because of these two measurements of line sag(s) and the coincident conductor temperature, then for any future projection of conductor temperature, such as during transient or steady state conditions, the future line sag can be predicted for any selected value of line current which may be higher or lower than the existing (present) line current. This becomes a very powerful feature, since future sags can be calculated based on existing weather conditions and selected higher or lower line currents. The line sag is calculated based on the CPS patented very accurate measurement of the slope angle θp (see Figure 18) of the line catenary with respect to the horizontal. This method can be applied to level spans, where the point of attachment of the conductor at the ends of the span are at the same elevation, or where the point of attachment of the conductor at the ends of a span are at unequal elevations. Only one STR Unit is needed, both in the former and latter cases. The Powernostics® Software calculates the line sag based on the measured conductor temperature of the line and compares this value to the measured line sag which is determined from slope angle of the conductor. If there is a deviation between the calculated and measured values of line sag, then the Powernostics® Software adjusts the value of the sag as calculated from the measured conductor temperature so the two values (i.e. sag measured from slope angle and sag calculated from measured conductor temperature) agree. This becomes a significant feature, because accurate values of sag can be predicted for any future value of current level with existing ambient conditions.
8	Line De-Icing & Prevention	Option A STR Units measure ambient temperature, solar radiation, conductor temperature, line sag, line current, humidity, and barometric pressure. In addition, Option A Transmission STR Units measure tower tilt, conductor swing, broken conductor, and conductor vibration conditions. Measured weather data from the STR Units can be used to determine the current required to thaw the line ice, and over what period of time the line ice will be thawed, as well as determine the current necessary to prevent ice from forming on the lines.
9	Tower Tilt/Broken Conductor	Option A TSTR Units measure any abrupt change in θ_p , the angle in the plane of the conductor sag measurement, and θ_s the angle perpendicular to the vertical plane of conductor. The θ_s angle measurements are an indication of the suspension insulator swing angle and conductor blow out. Other measurements include the conductor vibration frequency and amplitude.
10	Circuit Re-Configuration	Circuit re-configuration current and voltage data is more applicable for distribution circuits where the availability of information is lacking on both the circuit and its laterals. In most cases, the last point where data is commonly collected is at the head end of the circuit at the substation or at the line breaker. Basic DSTR Units measure the line current and fault current; and Option B DSTR Units add the voltage measurement, so Option B Units can provide all the power quantities and even lightning stroke current and voltage.
11	Capacitors/Regulators & DG's	The Basic STR Units measure current, and Option B Units measure both current and voltage, and as such provide all the power quantity data. Option B Units can be used to send data to control capacitors, line regulators and distributed generators.
12	Transient Data & Waveforms	Option B DSTR Units measure 23 parameters, and Option B TSTR Units measure 27 parameters.