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Carl

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  1. that sounds like a decimal addressing range..........it sounds like you should be using a hex range which is basically a function code and then a 8 bit hi and 8 bit low ....try that modmat software I'm sure that in a hex format....
  2. I recently finished a project on modbus I have a pdf files that could possibly help you ....how do I get them to you?
  3. Hello Gents, Just a quick one ....what is the fixed mains 230v ac wire color for a panel. What is the mains control color for 230V AC in new zealand. Thanks
  4. it could cause problems if you are switching the drive on and off via the mains contactor as a stop start thats if the duty cycle of the on off is very short..............I've seen this problem on the old mitsi drives ....it used to burn out the surge resistor.....and then in turn it would weld the surge contactor........and then it would pop the input bridge due to the repeatd high inrush current.....and if you where really unlucky it would feed AC to the capacitor bank....the caps would then explode.............fortuanatly I've only seen one catch on fire and that was on a work bench.......mind you the ringing in my ears lastd about an hour and my boss was not to pleased its called........... learning the hard way
  5. try this site: http://www.embedded.com/2000/0010/0010feat3.htm
  6. It is usual practice to keep the power and control cable separate as this reduces the likely hood of interference from the power cable…….as this can inductively couple……..especially in inverters as you have a rapidly changing signal on the leading and trailing edge of the output waveform to the motor……… if memory serves me correctly a square a wave is rich in odd harmonics. sorry I should have mentioned that cables running in parallel have a greater likely hood of causing interference……..basically it is a transformer in a straight line
  7. If it is an IGBT failure...then it is not uncommon for the chopper section of the pcb to fail.......thats if it is not one of those smart power modules, which usually have the chopper section built in the power module.
  8. you can get serial a/d converters have a look at analogue devices
  9. You would normally do a risk assessment… this should clarify what SIL you need and where you need it. The risk assessment should ideally be traced to some standard……..usually driven by the type of industry the kit is for.
  10. I would say as a general rule that any equipment that has the potential to deliver an electric shock, should be earthed where practically possible..........
  11. So one part is the anode let say the ship and the other part is the cathode let say the shore side. There is now a potential difference between the two bodies, because we do not have the same earth/neutral and the medium for the reaction is the salt water. Thanks for the comment Mark appreciate it
  12. Hello Gents I just finished a job on a ship.....I got involved with the generators and an interesting observation was made. There is no neutral on the generator...this is due to a chemical/electrical action (electrolysis). I was discussing this with one of the ships engineers and he was telling me that this is maritime law and aluminium ships will corrode within 2 years if there is a neutral to the deck but steel ships are OK. Does anybody care to comment? Regards Carl
  13. Morning Mark, If any cable is to be run have it on the mains rather than the motor side
  14. To answer point 1 According to PUWER regulation 19 Quote "Every employer shall ensure that where appropriate work equipment is provided with suitable means to isolate it from all its source of energy” etc The main aim of the regulation is to allow the machine to be made safe, under certain conditions Such as when there is maintenance to be carried out when a possible unsafe condition develops. I can not think of any technical reason why there should be isolation, but in the UK and other ECU countries you will most certainly will be breaking the law if you do not provide isolation and face possible conviction. Hope this sheds some light on the matter I’ve quoted the PUWER regulations you can have a look at harmonized standards , I’m sure it will be the same ther could be more detail as to where the isolation must be and the way it is marked color etc etc
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