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Hi all, I was wondering what is the best way to make a piezo sounder replicate the Zulu morse code signal dah-dah-dit-dit. I have tried using a decade counter driven by a 555 timer but found this a bit sensitive. I would even be open to the idea of something programable. The main specs are...

Hi All, I am designing the electrical components for a 200 kW grid connected hydro scheme. I have done a cost comparison using a synchronous (genset) generator and an induction generator (with caps) and the two prices are very comparable. My preference is to go with synchronous as this is...

Hi All, I am designing the electrical components for a 200 kW hydro scheme. I have done a cost comparison using a synchronous (genset) generator and an induction generator (with caps) and the two prices are very comparable. My preference is to go with synchronous as this is what I am familiar...

Hi all, I have an application where we sense rotational speed by using an inductive proximity sensor to send pulses to a counter card on a plc every time a gear tooth passes the prox. The problem I have is that the resolution is a too low and our speed output is not accurate enough. I have...

Hi All, I am trying to get my head around RS485, especially earthing. I have a simple question that should help me clarify some misunderstandings. If I have one PLC powered by a battery and another powered by a seperate battery that are connected by RS485 (2 wire only) will the communications...

Hi all, I am in the situation where we are wanting to determine the fault ride through capability of our synchronous generator. I know that these things can be modelled using the inertia of the generator, AVR charecteristics, etc. But how would you go about testing this in the field? Do you...

Hi all, Is there a rule of thumb to determine the maximum real power output limit of a synchronous generator (at unity power factor) before the load angle becomes too big and synchronism is lost. E.g., 2 x rated kW

Hi all, I am wondering for a generator of fixed rating, does an induction generator or synchronous generator have better fault ride through capability. I imagine it would rely quite heavily on the inertia of the rotor. So which topology has a the highest inertia rotor. Also a synch genny...

Hi all, The following is some manufacturer data for the losses of a synchronous generator at different loads. What I want to know is what power do I need to rate a pony motor that will drive this generator to synchronous speed? Obviously its continuos rating needs to cover the friction and...

Hi all, I have a discrete representation of an analogue PI control algorithm. On the surface it looks very much like a velocity algorithm except for the integral part which is: Ki*Ts*(E1+E2) I was expecting to see: Ki*Ts*E1 What affect will this have? And why has it been done like this...

Hi all, I have just read something that has really confused me. I am researching transient stability of synchronous machines by reading "Power System Analysis" by Grainger and Stevenson. Pg 718, describes a system where a generator supplies a bus with 3 transmission lines, two long...

If I have an induction motor (500 kW) being driven at exactly synchronous speed, what sort of starting currents would I be likely to get if I start it DOL? What happens if the speed slightly varies from synchronous? I have been told by an engineer that at synchronous speed the starting...

I was wondering if the terms synchronous generator and alternator are interchangeable. I work in an office where the mechanical engineers perfer to call it an alternator whereas I simply call it a generator (leave out synchronous as we are only working with one type).

If I use an induction motor with a variable frequency drive as the prime mover for a synchronous generator. Can I use the VFD as a way of regulating the power generated? I.e., can I increase speed to reduce the power generated. This is for an electric test rig.

Hi, What would happen if you have a leading power factor feeding an induction motor?

Hi, I am wanting to drive a DC motor as a generator to charge a battery for some data logging equipment. The system will be 12 Vdc. I intend to generate with the motor at higher than 12 Vdc and feed this directly to the battery. This may mean a 15 V motor or I may run a 12 V motor at higher...

Hi, I am after a synchronising relay that will operate when frequency, voltage and phase angle are in specified tolerances. A function to set contactor closure time would be useful too. I do not need a synchronizer as voltage and frequency are already controlled, all I want is a unit to...

Hi, I have a 500kW generator that is going to need synchronising with the grid. I have the recommended synchronisation parameters from the manufacturer but I tend to think that the frequency tolerance they have given is a little low (+/- 0.1Hz). Is this a typical value? Thanks

Hi, Could someone explain what 3 phase sensing is to me in terms of an automatic voltage regulator for grid generation purposes. I have read that it should be used when a load is non-linear and fluctuating, but I don't understand why this requires 3 phase sensing? If the generator has a...

Hi, Could someone explain what 3 phase sensing is to me in terms of an automatic voltage regulator for grid generation purposes. I have read that it should be used when a load is non-linear and fluctuating, but I don't understand why this requires 3 phase sensing? If the generator has a...