the voltage between the neutral & the power leg is 1. Voltage between two Hot Phases = 120V x 2 = 240V (1-Φ). In this configuration, the PT primaries and secondaries are both wired in wye configurations. The fourth being "OFF". Each transformer is rated as 10 kVA (current rating is 10 A and voltage rating is 1000 V). Open delta- two xformrs, not broken. Gate pin is shorted to Source pin. 65,740/1,000=65. No. When connecting three transformers for three-phase use with a delta secondary, a voltage test should be done before closing the secondary. You now have a corner grounded 120 Volt Open Delta bank. Based on a discussion with the manufacturer the transformer can also be designed for two primary voltage levels (with change over secondary side). A buck-boost transformer can be wired in an open delta when the load is relatively low to buck the voltage from 240V to 208V. Commonly, for ground detection on an 11 kV circuit, the primary will be connected in wye. Using a power quality analyzer connected to the drive input, first measure at the input side of the drive. 0 Unported Licence. It does this by reducing the effects of any small errors present in the winding of either the primary or secondary coils of the transformer. in distribution networks is used and its winding tap is grounded to change the zero sequence voltage measured by the open delta voltage transformer for distribution networks. Open Delta is a 3 phase transformer bank using 2 transformers. 15-16 9 Two way and three way control of lamp and formation of truth tableExpt-6: 17-18 10 Expt-7: Study of effect of open and short circuit in simple circuits 19-22Voltage Measurement between Neutral to Ground. – 100:√3 V or 110:√3 V according to IEC for star configuration. When using an ammeter or a voltmeter, you will notice that these usually have buttons or dials to choose the range of. Electrical power is the product of voltage times current. A Delta-connected relay doesn’t see the Wye voltages, so we’ll remove them in Figure 6-9, which is a good representation of what the test-set thinks is happening using Delta voltages and Wye currents. For typical delta/delta systems, the ratio is 2:1 — but for typical delta/wye systems, the ratio is 4:1 (Fig. With all the three transformers connected in delta, the power delivered to the resistive load is. Usually, the VT ratio of primary V LN: 69. 2n. Two identical 1-phase transformers connected in open delta will serve a 3-phase motor load of 250 hp. The meter will provide per-phase voltage, current, power, and energy readings scaled to correspond to the medium-voltage measurements. Open delta or wye transformers; Low torque output causing mechanical stresses;. The true subsurface resistivity can be estimated by making the. U 2n = 110 / 3 V. The high leg is a nominal 208V to ground. The voltage induced in the transformer secondary or on winding one is V ab. (open delta) and serving a delta connected impedance load. software to measure the dielectric properties of materials. L2 L1 L3 Fault condition L2 L1 L3 Healthy condition L1 L2 L3 U. They are characterized by low short circuit voltage and low nominal. edu. 0 V olts. The capacitive potential divider is used to divide the high line voltage to reduce it below 10kV. This parameter will be used to sweep the dc value of the voltage at input node A. The supply voltage of the transformer is 480/277 V. If the phase to phase voltage of the service needed is 2 times the phase to neutral voltage of the service needed, how should the secondary be connected? 120/240 volts. Connect voltage inputs that are wye-connected, open-delta-connected, or single voltage. Setting Values-V 0 - 6. High Leg Delta vs Open Delta. Re: Difference Between Closed Delta and Open Delta Arrangement of Elements. Feb 13, 2015. 1. Don't know what the OP is asking. Now you still measure 120 volts from line to neutral from either line, but from line to line where you previously read 208 volts, you now read 120 volts because the phase angle has been changed. Feel like buying Chris a coffee? Think of it as SchulerRuler fueler! transformers in this guide are de-signed to transform primary voltages from 5 – 34. Exercise 1 - Voltage Regulation Characteristics; Exercise 2 - Characteristics of a High-Voltage AC Transmission Line. The instrumentation which is installed in the plants is generally of electronic or digital type which has reduced consumption on the secondary of the measurement transducers, CTs and VTs (in general. Agilent measure-ment instruments, such as network analyzers, LCR meters, and impedance analyzers range in frequency up to 325 GHz. However, Y-connected sources can deliver the same amount of power with less line current than Δ-connected sources. Additionally, sophisticated decision-making algorithms, e. Turn the dial of the multimeter to monitor DC voltage. A V-V system is another name for an open delta connection system. Delta transformer balancing. Even though 0A will be output, select an. 11/05/2014 1:07 AM. 100 KVA d. 1 in. To properly size a delta/delta transformer, the transformer phases (windings) must be balanced. 5 Definitions of voltage, current, resistance. 2. Delta wiring forms an equilateral. Accommodate wye-, delta-, or open-delta regulator configurations. Capacity of open delta system = 0. One a typical 120/240 volt single phase transformer, When the two secondary coils are connected together in series inside the tank, the the secondary voltage. Electrical resistivity surveys map the subsurface structures by making electrical measurements near the ground surface. In this application, an open delta PT connection is used to detect zero-sequence voltage at the generator terminals. 73=65,740. The observed frequencies are subdivided into various groups: alpha (8–13 Hz), beta (13–30 Hz), delta (0. The transformer load is split across the three input phases. 3. 6 Interpretation of the measured values 36 3. When looking at the raw data in the trigger trace function it shows single Va, Vb, and Vc phasors with L-L values. The voltage to ground of a high leg or "stinger leg" on a three phase open delta system will be approximately: 208 Which of the following is the symbol for impedance? Open Delta is a wiring technique that uses three different transformers to provide a 3-phase voltage supply from a single-phase power source. This shift can be detected by measuring the Voltage across Grounding Resistor Or from the generator terminal Open Delta voltage. Determining self-discharge involves making just two open-circuit voltage measurements, but one must consider relaxation and voltmeter accuracy when grading cells. Also, one or both of the ungrounded phases may indicate low power factor because this type of. Voltage transformers with two secondary windings, one for connection in Y and the other in broken delta can then. The star point forms a floating neutral. can you tell me what is happening verified all in coming voltages they are good . Vab = Voltage across open delta terminal. 6%, i. They, too, provide 3-phase transformation, but the. Connect N to B phase. Potential or Voltage Transformer: The purpose of the Potential Transformer is to provide an isolated secondary voltage that is in-phase and exact proportionate representation of primary voltage. 031 kW. This isolated shunt based current measurement unit enables high accuracy current measurement without the use of Current Transformers (CT). 118 synchrophasors, and is the economical solution for overcurrent protection. The secondary windings of a transformer with voltage ratings of 120/240 volts must be connected in series to supply 208-volt, 3-phase power on a 4-wire service line. 7% of the capacity of a complete Δ-Δ circuit of the same transformers. 73. So the three phase of the open delta three phase system is being used for other facilities. 66 KVA. When you have a triangle of 3 resistors (a, b, c), and nodes A, B, C. Notice that the B-phase secondary is grounded. 16. However, the reference to Vcb is just to denote that the common connection of the open delta PT's is "b". 00E–06 3. Figure 1 Open-delta PT connection In an open-delta PT connection, V A, V B, and V C voltages are connected to the VA RELAY,VB RELAY, and VC RELAY inputs. To make the transformer connections compatible with three-phase supplies we need to connect them together in a particular way to form a. Potential or Voltage Transformer: The purpose of the Potential Transformer is to provide an isolated secondary voltage that is in-phase and exact proportionate representation of primary voltage. High-precision battery cyclers can maintain constant currents with very little variation and can measure and store voltage and current with very little measurement. The voltage across the open delta will be 110 volts. on and measure the voltage across the rheostat. We were thinking of using 3 auxiliary transformers connected to the secondary of the PT's. Resistor a is connected between nodes B & C; resistor b between A & C, and c between A & B. 50/60/400Hz Vs DC Vs Variable Frequency. A typical open-delta PT connec-tion is shown in Figure 1. 00E–06 –1. Operation Criteria for relay-Figure-5. Many motors (and some transformer windings) are connected in either a Delta (Δ) configuration (Figure 2, left) or in a Wye (Y) configuration (Figure 2, right). The star-delta starter has both advantages and disadvantages. The performance of. The open delta configuration provides a simple means of voltage control, especially when more than one starting voltage is required. The voltage drops across all three resistors should add up to the supply voltage as defined by Kirchhoff’s Voltage Law (KVL). For reliable resistance measurements, the voltmeter must Voltage (V) Time 4. Typical Setting: 5% with 1 Sec TD 100 % Stator E/F ProtectionThis is how we can obtain the three different voltages for this system; however, we can also have a corner-tapped Delta configuration. cn). 2 [16, 17]: Interconnected network topology is adopted in HV transmission networks to provide a secure power supply in the event of an outage, as there are multiple paths to transmit electrical power. The measurements were conducted in argon-purged 0. The voltage across open Δ should be zero. e. The NI 9225 is rated for 600 V ch-ch isolation, so this voltage is within the safety specifications. In a static electric field, it corresponds to the work needed per unit of charge to move a test charge between the two points. The simple explanation is under nominal conditions (NC) we have a wye-delta configuration and open the delta at one corner to measure the summed voltage of zero under nominal conditions. 1 M NaOH aqueous solution (Sigma-Aldrich) as electrolyte. 90 posts · Joined 2007. On a Wye it reads 120 deg. The second secondary core is intended for a residual voltage measurement utilizing open-delta connection on 100:3V (approximately 33. Most people are accustomed to the single. Therefore a voltage transformer secondary voltage of. A three-phase transformer is simply three single phase transformers. third-harmonic measurement at the terminal (VT3) is available. Then, if needed, measure at the service entrance. No. If the loading question 7 is connected in wye, what would be the line voltage and the line current supply in the load? 104. or. Like voltage, current can be AC or DC. Dec 4, 2020. Delta-Sigma VDD_2 = 5. So the magnitude of the torques produced will be the same for a given measure of voltage supplied. So on A phase to ground you have straight 480V. A transformer that is 1,000 V nominal or less may be located on walls, columns, or structures in the open and does not require ready access. So to recap, we will get the following voltage if: V ωB = V BC V ωΑ = V ωC =− 1 2 V BC = 1 2 V BC ∠180° The fuse in line A operates open and creates an open phase or single phasing condition480V 3 Phase Delta. Figure 20. 8 kV) connected Phase A to Phase B on one. 1. The voltage at the broken delta becomes 3Vo or three times the phase-to-ground voltage. In the case of VTs with two secondary windings (one secondary winding for measurement, and one residual voltage secondary winding also known as a tertiary winding), it is advisable to connect a resistance to the terminals of the open delta connected tertiary windings of the three transformers (see figure 2 below). L2 L1 L3 Fault condition L2 L1 L3 Healthy condition L1 L2 L3 U. For. 00E–06 2. The zero sequence current of. The measurement speed of the voltmeter is critical in determin-ing total cycle time; faster voltage measure-ments mean shorter cycle times. Did he bring in the correct 2 phases (i. The terms line current and phase current follow the same logic: the former referring to current through any one line conductor, and the latter to. The voltage you measure will often vary with the loading of the system (on a perfectly balanced 240V delta you might measure 138V to ground). Draw the connections on the diagram below to create an Open-Delta to Open-Delta transformer bank using three single phase transformers. 03%. 2) Because this is 3-phase the difference in phases is 120 degrees. The utility may be providing an Open-delta or an open-wye on their side, but it is definitely 3-phase. This technical article describes the basic principles of three-phase systems and the difference between the different measurement. We have two existing PT's connected in open delta (connected line to line (A with B) and (C with B)) to a transmission line but we need to measure the line to ground voltage of all three phases. Voltage imbalance is the measure of the voltage differences between the phases of a three-phase system. 20 and 100 μV. Meanwhile, high-voltage batteries are used to store that energy. In the substation, three single-phase transformers are connected in star- star Configuration and supplied three-phase power to consumers. Returning to our paper example, the measured length of the paper could be expressed as 11. Single Phase Voltage and Single Phase Current _____ 6 2B. 5 Volts. If the line-to-neutral voltage is 240Vrms, then the line-to-line voltage will be 416 Vrms. That is why a 3-phase motor can be connected to a delta, open delta, Y (or 'star', or 'Pi') system,. Utilize the transformers on the Three-Phase Transformer Bank and the Resistive Load to connect. Typical coverage 95% Of Stator Winding. The maximum load power that can be supplied will a. Not sure if that's the technical name or not. #18. The open delta. Line impedance stabilization networks are commonly used for two main applications, emissions measurements as well as conducted RF immunity testing. In star connection, the phase to neutral voltage is about 58 % of the phase to phase or line voltage. A common three-phase source connection scheme is the Delta high-leg or Four-wire Delta, where each phase coil outputs 240 volts: Identify the different voltages obtained from this coil configuration, and which connection points each voltage is. We fit Neutral Voltage Displacement protection on our 33/11kV delta-star transformers in order to detect and clear earth-faults backfed from the 11kV busbars. ; 1mA = 1 milli-amp – which is equal to one thousandths (1/1000) of an Ampere. 577 x rating of closed delta system=0. Voltage imbalance is the measure of the voltage differences between the phases of a three-phase system. The 120 volt loads can only be served from one phase of the three phase primary. The meter will provide per-phase voltage, current, power, and energy readings scaled to correspond to the medium-voltage measurements. , the power leg has no use electrically & is a by-product of a Delta or open Delta secondary. The open delta connection uses two single-phase transformers. Figure B2. A transformer can not act as a phase changing device and change single-phase into three-phase or three-phase into single phase. Figure 2 Phase-to-phase voltages in open-delta PT connection with IA as reference at power factor = 1 (ABC phase rotation) The relay calculates the actual phase- to-phase voltages , as follows:. Figure 2. SEL-751 Data Sheet 3For Delta Power Measurements. – 120 V according to IEEE for open-delta and star configuration. and one for the open delta voltage signal. With respect to the A -phase current (I A) as reference (0 degrees) as shown in Figure 2, inject the following voltages into the relay, where 120 V is the nominal phase -to-phase secondary. e. This is a measure of the voltage applied to the detector to amplify the small circular dichroism signal. The Osilloscope's Graph. . See Figure 4. is often used in high-impedance grounded systems and U 2n = 110 V in effectively grounded systems. The number of turns also gets reduced by 42 % of the number of turns in delta connection. This amplifier is ideal for the direct connection of high voltage signals. If it still measures approximately zero, adjust the rheostat to minimum resistance and measure the 3 secondary line-to-line delta voltages. If you are talking of stepping up in the sense of Generator Step Up Trafo, then one most say it is Star Delta Transformer as in Transformer we always need to mention HV winding side connection first and in GSUT,. If either side of the PT were wired in a delta, it would cause a 30° voltage phase shift and incorrect readings. Coupling capacitor voltage transformers (CCVTs) commonly have double secondaries for both phase and 3V0 voltages (see Figure 2c ). Single- phase loads are connected to one leg of the wye between line and neutral. We're working in an old mine machine factory, recently converted to a gear shop. Then the. Same as with two 9V batteries, it's 18V between ends, 9V over one battery and 0V center, and -9V between other battery and 0V center, and you are able to measure polarity because it's DC. The open delta voltage transformer configuration consists of two (2) double bushing VTs connected as shown in Figure 1. This shift can be detected by measuring the Voltage across Grounding Resistor Or from the generator terminal Open Delta voltage. The topics covered in this post are. #1 I have been working with a power meter recently that has the voltage inputs from an "Open Delta" 3-wire PT arrangement. 2kV through a high voltage switch to a 13. The torque equation for a negative-sequence voltage polarized directional element is: 32QT V I V I MTA=•• ∠− −∠+22 2 2[]cos()()( ) MTA = angle of maximum operating torque, dependent upon relay designA Delta-connected relay doesn’t see the Wye voltages, so we’ll remove them in Figure 6-9, which is a good representation of what the test-set thinks is happening using Delta voltages and Wye currents. As a temporary measure, when one. Averaging voltage measurements (from SMU2 and SMU3) taken at both a positive and negative test current will correct for voltage offsets in the circuit. rsd =U. tinfoil (Electrical) 16 Jan 06 14:30. The maximum HT cutoff values for individual CD instruments differ, but they correspond to the maximum. This page titled 7. 3 = 208 V. Some power monitors have the capability to directly measure the ground current. The wye configuration gives a better voltage balance than the open delta configuration. A vector amplitude calculation. The complication in these things is that there are a number of ways of winding them, and a number of. Open delta is also used in industrial applications to form a delta-delta transformer connection when both the primary and secondary transformers have similar voltage ratings. The overvoltage relay is tuned to the third harmonic. The principle for an open delta winding - Voltages at ground fault in a direct grounded system . For voltage metering using open delta. An open delta connection only has 58% of the capacity of a full set of three. That's a unique feature of Dewesoft X. delta. c. Line to line voltage measurements can now be obtained using the 3 phase wye mode of measurment. c. Residual Voltage & Open Delta Voltage Measurement. This is another method of closing the delta triangle. The remaining phase-to-neutral voltage will be √ 3 /2 the phase-to-phase voltage. 3 = 208 V. 173 kVA Select from the following choices Choose the correct. Calculating Power in Balanced Delta Three Phase Circuits _____ 21 3C1. Trip logic for philosophy-3. With the power off and the primaries still wye connected, open the delta and reverse the connections for one of the secondaries, but leave the delta open. 577. Like the LTC2997, the LTC2990 and LTC2991 make all necessary measurement and temperature calculations internally. the two between which is the ground tap). The basic design topology of the VFD with a diode bridge, DC bus capacitors and insulated gate bipolar transistor (IGBT) output has proven to be reliable and beneficial from application and financial perspectives. Thus if we have a ∆-∆ transformer, and we re-move one leg of the delta, then we have a V-V transformer (also called an open delta trans-former). The voltage is initially given by Equation ( ef{1. Measure and calculate the Open Delta voltage unbalance frequently and consider installing a VFD if the unbalance is more than 1 percent in the three-phase circuit. 7 kV/95. You can only measure three voltages, 1-2, 2-3, & 3-1. An open Y-∆ connection requires only two phases plus the neutral on the primary side of the bank in order to develop a three-phase voltage at the. Exercise 2 - Three-Phase Power Measurement; Exercise 3 - Phase Sequence; 86364 - Three-Phase Rotating MachinesOpen-circuit voltage is then a measure of the amount of recombination in the device. The open delta has no circulating current. The PTs are magnetically isolated, and each PT input has a nominal voltage of 115 V RMS. AFAIK, most utilities will NOT provide an 'open delta' connection for new services, (and furthermore many will not provide new 'delta' 3-wire services of any kind), due to the problems with the 'stinger' phase as described above. Snyder, PE PDH Online | PDH CenterThe open delta configuration is used for small motors, and the wye configuration is used for large machines. The phasors are added either Vab + (-Vcb) or (-Vab) + Vcb. Question 10. Open manual. The two design simulators are replicas of the 12 kV electricity. It does this by reducing the effects of any small errors present in the winding of either the primary or secondary coils of the transformer. Measure voltages as high as 8 Vac rms. If it still measures approximately zero, adjust the rheostat to minimum resistance and measure the 3 secondary line-to-line delta voltages. Voltage is the potential difference between two points of a circuit. A differential input is balanced because the gains and. Phase and negative-sequence voltage and current are shown. Connect the wattmeters as shown in Figure 12. When the measured current is relatively small, connect the current measurement terminal between the voltage measurement terminal and the load. g. The high-leg delta (also known as the wild-leg, stinger leg, bastard leg, high-leg, orange-leg, red-leg, and dog-leg delta) is a three-phase electrical service connection. I might add that normally these 3 transformers would be built as one chunk of steel with 3 sections, one for each phase. It can only come from a true three phase utility service. So the three phase of the open delta three phase system is being used for other facilities. It’s a AKD-8 switch gear line up, 13. where 120 V is the nominal phase -to-phase secondary voltage: • V A – V N = 120∠30 (ABC), 120∠–30 (ACB) • V B – V N = 0 (ABC and ACB. Impacts of measurement accuracy, sensor sampling frequency, and missing data on. Following are the applications in which open-delta system is used −. The V-V connected transformers are used to supply a combination of large 1-phase and smaller 3. Electrical Engineering questions and answers. 73 as there will be two elements across each phase. The utility may be providing an Open-delta or an open-wye on their side, but it is definitely 3-phase. or an open-delta connection of phase voltages cannot be made. Delta Star is mostly used at Medium Voltage level e. The residual voltage of a system is measured by connecting the secondary windings of a VT in ‘broken delta’ as shown in Figure 4. Discussion of how the three phases are still produced in an open Delta transformer. We will focus on the measurement of the voltage vu as indicated in the above circuit. Split-Phase 3-Wire System (1P3W). Pi and T networks (the names come from their appearance) are alternative ways of drawing delta and wye networks. AFAIK, most utilities will NOT provide an 'open delta' connection for new services, (and furthermore many will not provide new 'delta' 3-wire services of any kind), due to the problems with the 'stinger' phase as described above. 1 the associated cross-section of a FET with the. zero volts. This Open Delta Connection, which is rarely encountered anymore, is shown in Figure 9. 1 General requirements on equipment 37 A 3. 480V 3 Phase Delta is a 3 Wire power configuration and does not include a neutral wire. (The total load carried by open delta system is 57. The three-wattmeter method requires voltage measurements from line-neutral. Unbalanced single phase loads can cause voltage fluctuations and additional, uneven transformer heating. A 3D model WattNode meter, with the appropriate voltage range, will correctly measure grounded delta services, but the measured voltage and power for the grounded phase will be zero and the status LED will not light, because the voltage is near zero. In a true ungrounded delta system, a voltage to ground can actually be measured. Voltage transformer with two secondary windings, one Y-connected and one Open delta connected Figure 5. Location Ann Arbor, Michigan Occupation EE Aug 17, 2018 #17. User manuals, specification sheets, CAD drawings and more. A), voltage inputs (100-150 V),. Connecting the probes without ground lead to the individual phases should be safe (though with limited common-mode rejection ratio), as long as you observe the overvoltage category rating of both the probes and the scope. Any two legs will give you the phase to phase voltage either 208 if it's a "Wye" transformer or 240 if it's a "Delta" connection. g. The open delta is popular because only two transformers are needed. C phase to ground you have 480V. Three VTs or three CCVTs, such as shown in Figure 2a and 2c, pass positive-, negative-, and zero-sequence voltage. voltage and current values during this entire discharge/charge process, the OCV–SOC parameters are obtained. 5, 1. Using an overlap of 99% at a 50 Hz measurement you can calculate the power values for every 0,2 ms. What is Delta Connection (Δ)? Delta or Mesh Connection (Δ) System is also known as Three Phase Three Wire System (3-Phase 3 Wire) and it is the most preferred system for AC power transmission while for distribution,. They feature four and eight measurement channels, respectively. This can be used to simplify resistance measurement. 3-phase 4-wire system line-to-line voltage measurements are often a vector calculation of the line-to-neutral voltage measurements. In addition, the H2 bushing terminal (the third bushing terminal of the Delta winding) is grounded. The SEL-351A Protection System has built-in Ethernet and IEEE C37. How does the result change? Take a snapshot. Conceptually, the delta measurement is far more accurate than the single measurement, because the delta measurement cancels the saturation current and all. Typical Setting: 5% with 1 Sec TD 100 % Stator E/F Protection This is how we can obtain the three different voltages for this system; however, we can also have a corner-tapped Delta configuration. Even though the voltage transformers are connected line to ground, it is recommended that the transformers’ primary side have a voltage rating at least equal to the system’s line to line voltage. slavag (Electrical) 6 May 08. Nyquist plot of the built RC-circuit obtained by electrochemical impedance spectroscopy. 32 kVA. Changing the Voltage Measurement Mode in ATPOL II. Most VTs are designed for 60 Hz but can also be designed for other frequencies. As long as these two assumptions hold true, then the magnitude of the line to line voltage is 1. VB RELAY is connected to VN For this structure, the voltage waveforms in the open delta circuit and the phase voltages on the primary side of the voltage transformers were obtained, as shown in Figure 11 and Figure 12. in units of watts. In the utility metering and relay world, Delta and Wye refer to the phase relationship produced by transformer winding configuration. 120/240 V 3 phase is a red leg delta system. Other types of three-phase supplies are wye connections, ungrounded delta connections, or corner-grounded delta ("ghost" leg configuration) connections. neutral wire may be needed for three phase 240V outlets etc. A linear sweeping voltage is defined by the voltage (or potential) being varied linearly at the speed of the scan rate. The capacitors are connected in series at the primary side of the auxiliary transformer. However, a slightly more compli-cated approach is required when dealing with open-delta PTs. 3 in. up to 33kV. An open Delta Transformer is a conventional three phase transformer manufactured to give a single phase output. At the open circuit stage, the relationship between the OCV and the SOC is needed. The difference between two points called as potential difference or voltage drop. The ATPOL 8. The open delta system provides a total of 75% of the basic rating of the full system. Three-phase machinery typically runs from Delta voltage, a configuration using three hot wires and no neutral wire. The open delta voltage transformer reduces the AC voltage and large current proportionally to a value that can be directly measured by the meter ( automatic. Voltage does not affect the RPM of a motor, but the frequency of the voltage does. or cable end is indicated.