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  • Users: 7JLAman4
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  1. 7JLAman4

    Calculation of Equivelant Impedance

    Sorry. Z12 and Z23 are bus tie cable impedances. There is a breaker on either side of the bus tie cable.
  2. 7JLAman4

    Calculation of Equivelant Impedance

    anoter- Understand Case1. That is what I currently assume. Re: Case2 and Case3 I'm confused. If the bus ties are open, wouldn't the Zeq at any of the busses only be Z1, or Z2, or Z3? or did you mean to state that the bus ties were closed for Case2 and Case3?
  3. 7JLAman4

    Calculation of Equivelant Impedance

    Typically I assume that the buss ties are negligible and therefore Z1, Z2 and Z3 are easily paralleled for Zeq. I was just looking to understand how to compute if I were to assume buss tie impedance.
  4. 7JLAman4

    Calculation of Equivelant Impedance

    Sorry if you might have misunderstood. This is not for homework. Just looking to do something by long-hand rather than always using EasyPower, EDSA, or SKM. This is not my usual set of calculations. Looking to better understand what I may not have been taught properly before.
  5. 7JLAman4

    Calculation of Equivelant Impedance

    I'm attempting to calculate Zeq at the buss level. I have three generator impedances (Z1, Z2, Z3) connected in parallel and the cable impedances (Z12, Z23) connecting each of the generator busses. How do I calculate Zeq at the buss? Are they all in parallel or something else? Z1 nodes 0-1 Z2...
  6. 7JLAman4

    Safety Procedures

    Not certain if this is the place to post, but...I'm looking for something that I might be able to better help me pull together a document for a land based test site electrical equipment (panels, cable) installation that identifies procedures related to safety, commissioning/checkout...
  7. 7JLAman4

    Transformer Wiring

    I have a 3-Ph motor controller for 200-240V. I only have 120V 1-Ph available. In an effort to program the inverter prior to installation, the inverter is able to function with 240V across L1 and L3 terminals. Not looking to connect motor yet, just preset the drive parameters. I had cut an...
  8. 7JLAman4

    Transformer Wiring

    I was just typing as it came across. I noticed you mentioned rewound, and I was thinking for rewire! It is an isolation transformer, 117/117V, single phase, 6A, with a shield. Looking to use it to get 220-240V to an outlet. Not a permanent installation, just a shop toy.
  9. 7JLAman4

    Transformer Wiring

    Yes I have access to the primary and secondary wires. The transformer is small and only rated for 6A at 117V.
  10. 7JLAman4

    Transformer Wiring

    Is it possible to rewire a single phase isolation transformer to provide a 1:2 voltage output ratio.
  11. 7JLAman4

    General VFD Question

    General question regarding PWM VFD (inverter)operation. Using the constant torque setting (V/f), does the input current of the inverter increase as the output frequency increases? and if so, then is it proportional to the output frequency?
  12. 7JLAman4

    Calculation Method of Unbalanced Panel

    davidbeach- 7anoter4- The following is an abbreviated version from an IEEE Std ., which is the basis for our calculations. When sizing the feeder cables, spares are included when determining the panel demand load which is the basis for sizing the circuit protection and feeder cable size. If...
  13. 7JLAman4

    Calculation Method of Unbalanced Panel

    rbulsara- I do not believe that I had mentioned anything about a heater! The load is not a motor, not heater rather power supply or rack of supplies. My original inquiry was regarding the method for determining the load of the feeder neglecting any spares or demand factors to determine...
  14. 7JLAman4

    Calculation Method of Unbalanced Panel

    VTer: A1: The power panel is fed from a transformer bank consisting of (3)10kVA 480/120VAC single phase transformers connected to provide 3-Ph 3-Wire delta power to the panel. A2: In this case I agree with your approach for estimating assuming that the loads are closely balanced. If the loads...
  15. 7JLAman4

    Calculation Method of Unbalanced Panel

    I have a 3-Ph 120VAC Delta connected power panel. I was given a method for calculating/estimating the panel feeder cable 3-Ph load ampacity. My question is, how accurate is this method below? The 3 phase load was calculated as follows; for an unbalanced load on a panel, add the two highest...
  16. 7JLAman4

    Motor and Drive Selection

    Marke- Is it possible to acquire or design a PWM drive that delivers full rated torque or constant torque over the entire operating range of the drive or at low output rpms?
  17. 7JLAman4

    Motor and Drive Selection

    I would tend to agree, however I'm sorry for not mentioning that the motor is actually part of a larger shaft. This will be part of or segment of a longer drive shaft. Similar to a Power Take Off (PTO) configuration with the exception that the machine will operate as a motor , not generator...
  18. 7JLAman4

    Motor and Drive Selection

    I'm looking for assistance dealing with a motor configuration. I'm looking for ideas regarding continuous low speed operation of an induction motor, or what I think is low speed. The required motor is 700Hp at 100 rpm. I've got a supply voltage of 480VAC 3Ph 3Wire (delta). What I'm thinking...
  19. 7JLAman4

    Required Cable/Protection of Unbalanced 3Ph Panel

    Well thank you for the graphics! I have a Delta 3Ph 3Wire secondary 240V (L-L) that directly supplies a panel with resistive loads. When I calculate the line currents of the loads described in the OP, I calculate ILA = 97.6A, ILB = 90.8A, ILC = 79.5A. Typically I am accustomed to adding...
  20. 7JLAman4

    Required Cable/Protection of Unbalanced 3Ph Panel

    What is th proper method of determining the required/calculated cable ampacity of an unbalanced 3Ph panel. Assume a 3Ph-3W delta configured panel that has 15kVA PhAB, 10kVA PhBC and 12kVA PhCA. I understand the method of calulating line currents of unbalanced systems, but what is the...

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