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  1. scott88

    Standby Diesel Generator - Switching Loads Question

    The genset is Rolf Janssen, comprising of a Leroy Somer generator and MTU diesel engine. Protection relay is a Siemens 7UM62 with Siemens controller and synchro relay. The generator is already part of a system, my question is when switching regarding what load I can switch onto the generator...
  2. scott88

    Standby Diesel Generator - Switching Loads Question

    Can anyone offer any assitance with the absence of software? This is a permanent standby generator and I do not have access to software. Whilst looking into this I have given consideration to the sizing of a generator for a DOL motor and it is apparent that the required generator is...
  3. scott88

    Standby Diesel Generator - Switching Loads Question

    All, I have a 3 phase, 415V, 1100kVA diesel generator as an emergency standby,the diesel engine is 1000KW. Currently I have 7 distibution boards that are supplied by 2 incoming feeders from the 6.6kV board. 1 feeder is supplying 2 boards that are conected together by the busbar tie and it is...
  4. scott88

    Generator Response to a Change in Grid Frequency

    dpc Generator terminal voltage remained constant when the frequency change occurred, once the increased current had stabilised at 8.78kA it fell from 20.29kV to 19.94kV. Excitation current then rose and returned the generator terminal voltage to 20.64kV, it eventually stabilised at 20.3kV...
  5. scott88

    Generator Response to a Change in Grid Frequency

    Hi, I am looking for some clarification on my understanding of generator frequency response following a recent sequence of events. The generator is an 280MW machine with a gas turbine prime mover connected to the national grid. Following an instantaneous drop in grid frequency fromn 49.97hz to...
  6. scott88

    Generator capability whilst connected to national grid question

    Hi, Please could you help my understanding on the generator performance and change in p.f when connected to a grid system in the following scenario; A generator is connected to the national grid via a step-up transformer. The maximum achievable voltage at max power that can be achieved is...
  7. scott88

    Generator reverse power question

    Thanks for all of the answers, I appreciate the responses. If anyone else has a definite answer or knows of any studies into the effects on a generator at standstill with an open circuit rotor and back energising the stator please let me know. I am interested to know if the rotor would move and...
  8. scott88

    Generator reverse power question

    Hi, Thanks for the responses. So if the prime mover and generator were stationary, the rotor winding open circuit (Excitation isolated, brushes removed), my understanding is that because the rotor winding is open circuit, it would not be possible if the stator was re-energised to turn the...
  9. scott88

    Generator reverse power question

    Hi, I think my question is not very clear. I would like to know if the brush gear is removed so the rotor winding would be open circuit, and the generator circuit breaker was closed, is it possible to motor the prime mover? I am currently thinking not because it would not be possible to self...
  10. scott88

    Generator reverse power question

    Hi, Please could you help with a theoretical dilemma I am having; For the purpose of the question, imagine a three phase Ac generator with a rotor that is excited via a static excitation system and the dc supply fed via brushgear and slip rings. If the brushgear is removed, the excitation...
  11. scott88

    Power Factor Question

    Hi, I have been given a question that I dont fully understand or better put couldnt explain my answer 100% confidently , can anyone confirm and expand on their answer please; The effect of a sudden increase in load on an electrical generator not controlled by an automatic voltage regulator...
  12. scott88

    Transformer Selection

    Hi, I am currently investigating and will be looking to eventually procure a transformer to supply an immersion boiler. The primary supply is 6.6kV and the boiler load is 400V / 2.5MW. I have contacted Siemens with a request for a quotation for a) an oil filled and b)a dry cast resin...
  13. scott88

    Diesel generator differential protection trip help

    Hi, Thanks for the responses. I will keep you updated of any findings. We have performed terminal box inspections and general inspections. A differential of that size one would expect to find a fairly visual fault if it was the machine. We will change the phase of L1 CT today and see if the...
  14. scott88

    Diesel generator differential protection trip help

    Hi, We have a problem with our emergency diesel generator. The generator is a 1100kVA 400V 50 hz machine, manufacturer Leroy Somer with Siemens SIPROTEC 7UM62 relay protecton. On running the generator up it is stable and running fine for anything onload between 40minutes to an hour and then...
  15. scott88

    6.6kV Motor VSD Upgrade Advice

    Hi, Firstly thanks very much for the informative replies. Please could I ask you to expand on your answer to help me understand further, so is torque proportional to speed and power output. That's where I am slightly confused. How can I calculate if the motor is oversized or what motor would...
  16. scott88

    6.6kV Motor VSD Upgrade Advice

    Hi, We are in the process of beginning a feasibility study into upgrading our main cooling water pump motors to VFD and ideally removing the gearboxes as these are prone to failure. Motor Details; 6.6kV, 4 Pole, 1500rpm, 2200kw Pump Speed; 380rpm (Speed range would be 200-380rpm) My question...

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