Control Voltage Sizing - PSU/Transformer

Just some notes on Sizing Control Transformers:

Collect all information about items connected to Transformer. (415/110V)

• Protection Devices (E/L, Protection relays , Arc detectors etc)
• Contactors (If powered by this supply to reduce inrush currents on system)
• Undervoltage/shunt trip coils in MCB's
• Motor heaters as they could be fed form this TX

Once you have accounted for all items find the nominal consumption as well as the inrush Consumption.

Calculate all the nominal consumptions (Qty x Consump) 

This will give you the min. size of the transformer

Next step is to Calculate the Inrush to ensure that the CB does not trip with the inrush current at startup. In most cases the TX will be able to handle a large inrush for a short period.

Do the Calculations your self

Just had some Cable tray designs rejected. It was not so much rejected but under designed. In most cases the engineer will select the route the cabling will be installed and then it is the trades person/ site construction team that will determine the cable tray type and installation.

Based on this these have been undersized, the fact is there is too many cables on the Tray for the support.

Tray support can handle 270kg, The span is 3m so effectively we can only place 270/3 per meter on the try. Solution change the tray supports or put more cable trays in and add more supports.

Next time do the Calculations yourself! Even if it is just to check

Don't Let it get to you.

Today was a good day, OK so I am lying. I will be marking today up to experience and consider the fact that I must not let people whined me up!

You will come across people that are just there to waste your time. Today I can once again officially state that I don't know what I did! I did not produce anything, I may have cleaned a few shelves to make space for more paper work, that is it!

For me this is not a productive day! But I am telling myself "Don't Let it Get to You"

Get it In Writing

Every Direction/Change/Variation/etc you get from anyone always get it in writing! Document it! Store it! You never know when you will need it again.

Just some tips:

1. Keep a Diary
2. If not a Diary, keep a Note book and date every not or page
3. Minute everything in a meeting, If you are not in control of a Meeting/Minutes makes sure when the minutes are released, Review and Comment, these can be used to your advantage!
4. Request information in Writing, even an Email.
5. After a phone call, follow up with an email about what was discussed, this allows it too be in Writing!

Just Get it in Writing!

The Pilot

The question to be asked is "What did I Learn Today?"

READ THE CONTRACT

Rule No. 1

For me now is Read the Contract! Like all Jobs/Projects I undertake there is a underlying Contract. Read it, Know it, Be it. Always remember the Client will know it better then you.