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Hi All, We have designed some intrinsically safe instrument loop circuits where the sensor is cabled from the main DCS panel to a field panel just outside the hazardous area (in the safe area) where the intrinsically safe barriers are located. This then supplies the instrument in the hazardous...

Hi All, We are currently completing some feasibility designs for some mobile mining units for a Client of ours. We have done similar units before where the transformer was located on the mining unit and powered via a 6.6kV trailing cable. In this case, they want to have an offboard 22kV/433V...

Hi, Thanks for your response. I am pretty well versed in area classifications, but have come across articles where even though diesel is classed combustible and not flammable (ie. Non hazardous), there is the potential for an explosive atmosphere to form in a storage tank. Any other comments...

Hi all, We are completing a project for a client of ours for 2 x 3.4 million litre storage tanks and have to classify the zone in the tank. As diesel is a combustible and not flammable this normally would negate the need for classification, but there are a lot of differring opinions on forums...

Thanks ScottyUK. I do like the Sick gear, but this environment is very agressive and I am steering clear of anything that uses optics, hoping more to use something that uses ultrasonics or radar or other?

Hello All, I am working on a series of 3 mining units which are not mechanically connected (i.e. about 3m apart) but need to move in together at the same time. They are each about 3 stories high and 50m long and move along on caterpiller tracks and are fully manually operator controlled. The...

Hello All, I am working on a series of 3 mining units which are not mechanically connected (i.e. about 3m apart) but need to move in together at the same time. They are each about 3 stories high and 50m long and move along on caterpiller tracks and are fully manually operator controlled. The...

Hi All, A friend of mine asked me these questions, and I though seeing as I only have a general knowledge of the area I would throw it out to the Gurus: with vsd's how is the inrush current reduced during startup at low speed/frequ? Also, for a standard motor, can you exceed the absorbed...

Hi All, I am in the process of updating our business software. Currently we use Quickbooks for invoicing/etc and am looking to get another software package which tracks projects, labour, materials, etc and let me see where everything is at (including financials, etc). We are looking at...

Good Evening fellow engineers and intellects, I am currently working on a project where I have 3 large mining machines which process mineral sands. These are about 4 stories high and weigh about 400 tonnes each, running on caterpillar tracks (I have attached a picture to give you some idea)...

Hi All, I am doing the preliminary design for a mobile mining unit and trying to work out what to do with the earthing. The unit is running on tank tracks and moves about 30m every 3-4 days. Onboard there is a trailing cable running from an external cable reeler to a 6.6kV RMU (which also feeds...

Thanks for that DPC. As a little experiment, and to settle my curiosity, I decided to put some AC breakers to the test. I put a 4A AC MCB breaker in series with a multimeter in my battery circuit in my car (12VDC). As it turned out, the breaker does operate, and the times correspond to the...

Hi all, I am just curious of the effects of using AC MCB circuit breakers for DC applications (i.e. using a 4 Amp C-Curve AC MCB to protect a 24VDC control circuit). I am aware of the arc extinguishing problems at the high end of the scale but am curious (mainly because of the price difference)...