3-phase

  1. H

    MEM 3-phase board

    Morning all, As the regulars know, I work in a school part-time (while sparking part-time), and I'm going to do a bit work for them - they need power dropping in for 11 PCs. No problem, 2 RFCs should do to share the leakage currents of the machines, bit of dado trunking round the room, RFC...
  2. gazdkw82

    3-phase motor RPM=fx60/p

    just going through some mock exams to prepare me for the 202 exam I have next week. Came across the following question A 3-phase synchronous motor is required to operate on a 50Hz supply and run at 500 rpm. The number of poles required is: So I know the formula for this as RPM = Fx60/poles...
  3. D

    3-Phase Motor Testing

    Hi I'm Darren and I work as a apprentice for a manufacturing company. I was testing a 3kw 3-phase motor as it blew a fuse and when doing my IR test down to earth I got a reading of around 11Gohms. I was under the impression that the reading had to be above 1Mohm which this is as far as I am...
  4. R

    3-Phase Star Config.

    Hey Guys, Just been looking at the C&G 2365 L2 Textbook and don't understand the answer to one of the questions as given below: A 400/230V star-connected system has three equal loads of 11.5 Ω per phase. The line and phase currents will be, respectively: a) 34 A and 34 A b) 20 A and 20 A c)...
  5. S

    3-Phase / 400V ring main

    Hello, New here, but hopefully someone can help...! We have been tasked with installing a number of very small pumps (21 in total) on a large site. Running individual cables to the 7 areas (3 x 1.0kW / 400V / 3phase / DO.L. pumps in each area) where these pumps are located would be expensive...
  6. G

    3-Phase Supply Configuration, Mixed Commercial and Residential Installation

    I have a potential customer, in Scotland, with mixed commercial and residential premises. The property was formerly a pub with a property of multiple occupancy upstairs. The property currently has a 3-phase TN-C-S supply coming in to the DNO's fused distribution box in the attic, second floor...
  7. S

    63A 3-phase electrics possible through 6mm cable ?

    Hi, Is it possible to get 63A 3-phase through 6mm cabling/wiring ?
  8. S

    3-phase sub-main sizing

    hi chaps, I've got a 3-phase supply to get in and am not overly experienced in 3-phase cable calcs, basically the run is 60m, it will be buried, and it needs to run one 3 phase 16A boiler, a couple of single phase socket outlets and a couple of lights. hope somebody can shed some light
  9. M

    Mains on 3-phase DB

    Hi I am working in a hotel and I found that a 3-phase DB was fed by 2 seperate swa cables one containing the 3 phases and the other a seperate neutral and earth I know this is bad practice but can someone tell me why the NIC firm have picked this ad a fault I would not have done this myself it...
  10. B

    3-phase Roller Shutter Door - Opinions please

    Hi guys, recently been given a job to supply power to a 3-phase roller shutter motor in a warehouse. The cable path is to follow the a-frames of the roof on 50mm tray with girder clips (to span the warehouse) then tray along the wall to the motor.. must i use SWA? its a 75 metre run in total...
  11. S

    3-Phase Cowboys?

    Hi all, I was sent to a job the other day to put in a supply for a new 3-phase motor. Our projects department decided instead of installing a new circuit from the DB which was situated 10 metres away wanted me to cut an existing three phase 32A SWA supply, feeding another motor and install a...
  12. M

    3-phase motor question

    Can someone give me some advice please? I sat my C&G 2394 exam this week. Passed the practical, failed the multichoice by 1 question. Written paper next week. My question relates to one in the multichoice paper. What is the correct sequence for safe isolation on a 3-phase motor? Can't...
  13. D

    Earthing arrangement and single to 3-phase upgrade

    Newbie here - please go easy on me, and I hope I'm posting in the right forum! ;) Existing arrangement as follows - single phase TNC-S supply provided in a remote building. This building has a substantial 3-phase company supply, but my supply is tapped off the incommer, and through a a single...
  14. W

    3-phase Pannel Meters

    Hi Guys, I need a bit of statistical info: The main pannel in our rugby club ( MIC 150 kVA ) is fitted with an LCD meter ( displays: A, V, Power ( kWh. KVAr,kVA ) and a 4th screen I've not figured out yet ) where the main 3-phase comes into the pannel and also has the master On/Off Switch for...
  15. A

    3-phase worries for football stadium audio equipment racks

    I was recently surveying a football stadium and the amplification racks for two of the stands were in one location. The equipment was mounted in 3 separate racks each housing about eight 400 watt amplifiers (real long term power not home hi-fi peak/transient power) This makes for quite a...
  16. R

    Which type of Speed Controller required for 3-phase motor

    Hi all Client requested speed controller for 3-phase/4KW/7.9Amp motor running extractor fan to spray paint booth in local car mechanics Have been advised I require SYSTEMAIR RTRD 14 SPEED CONTROLLER VSD VFD IMO INVERTER DRIVE FREQUENCY Reconditioned and load tested unit available at £240.00...
  17. P

    Energy Consumption on 3-phase with solar into one phase

    Hi Quick question about a system a user wants who has 3-phase electricity. If we install a 4kWp system onto one phase, when it is generating more power than is being used by that phase, will the other phases consume that power, thus slowing/stopping the meter, or is it lost back to the grid...
  18. D

    3-phase power calculations

    Hi, I am a trainee electrician and have some questions concerning a 3-phase installation. I have been asked to calculate the maximum load of a supply at a factory and have the following information. I realise the best option is to use a clamp meter and measure the voltage and current load across...
  19. M

    4KW/16A and 3-phase

    Hi This is just a sanity check really. I want to install a 4kW system in a building which has 3-phase supply. Assuming I keep the inverter under 16A are there likely to be any issue with the DNO (Western Power!) over only pumping it all down one of the phases? Thanks
  20. B

    3-Phase Queries

    A 3KW, 3-phase, 230V motor draws approximately 13Amps (if my calculations are correct)............. I imagine this is the rating for each individual phase? What rating should I give my breaker? (Formula?) If I take two phases for my control circuit, which formula could I use to fuse my circuit?
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