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  • Users: Indy
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  1. Indy

    Public Address system wiring

    Good morning, I have a query about public address system cabling. What is the maximum distance that a loudspeaker can be placed from the control panel using 100v speaker cabling? Thanks
  2. Indy

    One Ner per Substation for two Transformers

    Hello, I have a question regarding the use of one Neutral Earthing Resistor per substation for two transformers. Can anyone point me in the direction of websites/ literature that would show the operational philosophy of this set up compared to one neutral earthing resistor per transformer...
  3. Indy

    11kV cable joints

    Hello, With regards to 3 core 11kV cables run in parallel on a ladder that need to be jointed. is there a standard to say what the spacing should be between joints ? Thank you
  4. Indy

    Switchboard fault rating

    Hi, I have a query in relation to MV fault levels for an 11kv switch board. How is the fault rating (x kA for x seconds) calculated from the following information: 3 phase fault Line to ground fault Line to line fault Line to line to found fault. For each of these scenarios we have I”k Ip...
  5. Indy

    Power over Ethernet CCTV

    Hi, I have a question about POE cctv systems tying into an existing site fibre network. I understand that a POE switch will be required for the cameras and also a Poe extender for camera distances greater than 100m from the switch but does anyone have an example architecture drawing to show how...
  6. Indy

    Earth switch

    Hello, Is it a requirement to have an earth switch fitted on 11kv fixed pattern switchgear as a contractor is saying an earth switch is only applicable to withdrawable switchgear. Thank you
  7. Indy

    Distribution board or main switchboard

    Hi, With regards to bs7671 are there any rules regarding when to install a distribution board? For example say we have a main switch board that is feeding pieces equipment separately but these pieces of equipment are quite local to each other would it then be better to take one feed from the...
  8. Indy

    Inter posing relay

    Hi, With regards to a Siemens DO card which has outputs rated 0.5A@24VDC if we are using these output channels to power 24VDC solenoid valves (0.3W &7w)would these require interposing relays as they are within the limits of the channel? Thanks
  9. Indy

    Cable question

    Hello, I have a question regarding instrument cable. I know that for 4-20ma transmitters twisted pair cable should be used with the screen grounded at one end only. However for digital signals ( limit switches , push buttons ) can 2 core/ part of a multi core cable be used ? Thanks
  10. Indy

    24vDc power supply and earth

    Hello, I have a question about 24vDc powering instruments from a control panel. My question is why do we use a 2 core cable going to the device/instrument and do not provide a 3rd for for the earth connection like would be provided if the device was powered by AC single phase? Thanks
  11. Indy

    Multicore cable earth

    Hello, We have a local push button station going to a PLC in a safe area. There is a 7 core cable connecting the station to the plc. Core 1 24v Core 2 spare Core 3 push button 1 Core 4 push button 2 Core 5 spare Core 6 spare Core 7 earth My question is why is core 7 an earth cable, can’t...
  12. Indy

    ET200 SP HA

    Hello, We have the following DI card that can accept 1,2 and 3 wire DI's ( 6DL1131-6BH00-0PH1). We plan on installing this card for use with think top head valve limit switch. From the valve( think top V50) manual it says that connections should be made to pins: 1 and 2 for power supply and then...
  13. Indy

    IO list question

    Hello, We have a vsd running signals to a plc. The signals are deemed soft io, they will be transferred over profinet to the plc. My question is how is this shown on the IO list as we can only choose from AI,AO,DI,DO For example do we say that the VSD running signal is a DI to the plc with a...
  14. Indy

    Design document question

    Hello, I have a design document question that is related to an Input/Output schedule.We have the IO type as SOV but there is also a soft IO associated with this SOV. Has anyone seen this before what could the soft IO be for? The limit switches are hardwired DI’s. Thank you
  15. Indy

    Design pressure and temperature and operating pressure and temperature

    Hello, I have a question regarding the design vs operating pressure and temperature in relation to temperature instrumentation (thermowell)on process piping. For example say we have a pipe where the max operating pressure is 7.3 barg and the max operating temperature is around 43 deg C but the...
  16. Indy

    Thermowell question

    Hello, With regards to thermowell wake Frequency Calculations how big a role does the process fluid density and viscosity in the calculation? Thanks
  17. Indy

    Pressure transmitter

    Hello, I have a general question about pressure transmitters. Does the density of the fluid being measured play a vital role in the selection of a transmitter? This information is put on the data sheet that is issued but for example the 3051 Emerson data sheet for the transmitter does not...
  18. Indy

    3300 XL 8mm Proximity Transducer System

    Hello, I have a question regarding 3300 XL 8mm Proximity Transducer System. From the data sheet, this instrument has a Ui of -28V. The 3500/04 barrier has a U0 of 27.45V. My question is Can this satisfy the intrinsic relation that Ui is greater then or equal to U0? Thanks
  19. Indy

    Cable inductance and capacitance values per km

    Hello, I have a data sheet for RFOU (I) cable, The capacitance, inductance values are only given for one pair and one triple for three different sizes( 0.75,1&1.5mm2)My question is are these values also the same if you are using a multi pair of the same cable eg 4,8,12 pairs as this information...
  20. Indy

    Intrinsically safe calculation.

    Hello, I have a question regarding intrinsically safe calculations to iec 60079. For example from instrumentation tools.com Evaluating conditions for Intrinsically safe Loop: Vmax must be greater than or equal to Voc Imax must be greater than or equal to Isc Ci + Ccable must be less than or...

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