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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

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...

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

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...

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...

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

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...

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

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

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

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...

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...

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...

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

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...

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

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...

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

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...

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...