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24Vdc Output Power supply of 20A and 5A

Thread Starter: how come   Started: 6/3/2009 4:51 AM   Replies: 6

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  6/3/2009, 4:51 AM
Joined 10/5/2006
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Dear all,

I am facing some problems on site and would like to seek some help.

1] The range of amps I need is between 20A to 30A
2] Because of existing panel size constrain i couldn't install a bigger size of power supply i.e 40A.
3] I get a 20A and 5A power supply from pheonix contact which able to fit into the limited space of the existing panel.

Now the problems i face are:-
1] Is there anyway to parallel the two DC output power supply Or circuit connection for them to work together?
2] I have siemens IM153,AIs,AOs,DIs,DOs card and PLC CPU in the existing panel. Is it ok if I use the 5A output with 24VDC to supply to PLC CPU,DOs,IM153 and AOs card?
3] And I use the 20A output with 24VDC to supply to AIs and DIs cards. I put 20A is because the existing panel input cards are connecting to sensors, transducers and other devices that also need to draw supply from the panel.

I appreciate someone could give me some valuable ideas or adviseslaugh.
Thank you very much!

with regards,
how come?


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  6/3/2009, 7:56 AM
Joined 5/28/2008
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Hello,
Can you please tell us here the available space at your cabinet to enable us to help you?
Anyway, you can use Smart type power supplies
6EP1334-2AA01 
SITOP SMART 240 W STABILIZED LOAD POWER SUPPLY INPUT: 120/230 V AC OUTPUT: 24 V DC/10 A 145.00 EUR 
You have to use 3 x 10A = 30 Amps. And you can make bridge between "M" of the three power supply. i.e. common zero.
Smart type power supply dimension is attached.
Regards,

Attachment: Sitop Smart.JPG  (22 Downloads)

Ayman Elotaify
MISC Egypt
www.miscegypt.com

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  6/3/2009, 8:24 AM
Joined 3/1/2007
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Also note as Ayman has done, the parallel supplies should be identical. Anyway here is an important exerpt from the manual that will help you in your design

The output cables connected to terminals "+" and "–" of every

power supply should be installed with an identical length and

cross-section (or the same impedance) to the common external

linking point.

•The power supplies connected in parallel must be switched

simultaneously using a common switch in the mains supply line

(e.g. using the main switch available in control cabinets).

•The output voltages of the power supplies must be measured

under no-load operation before they are connected in parallel

and are permitted to differ by up to 50 mV. This usually corresponds

to the factory default setting. If the output voltage is

changed in case of variable power supplies, the "–" terminals

should first be connected and then the voltage difference between

the "+" output terminals measured under no-load conditions

before these are connected. This voltage difference must

not exceed 50 mV.

Note:

With a direct galvanic connection in parallel of more than two

SITOP power supplies, further circuit measures may be necessary

for short-circuit and overload protection!

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  6/4/2009, 11:39 AM
Joined 10/5/2006
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Dear all,

Sorry that I didn't highlight a point of why I choose phoenix power supply instead of siemens. I need a power supply that can give me the amps that I want and can operate in -25 deg. I check with my local siemens supplier but they told me don't have SIPLUS power supply with the amps I want and can operate at -25 deg. The other I/O modules I have are all SIPLUS. The two power supply that I have from phoenix are able to work at -25 deg. Thus the problems I face now are what I have address earlier.laugh  I appreciate you could help me and give me some ideas
Thanks!

With regards,
how come?
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  6/4/2009, 12:52 PM
Joined 3/1/2007
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Actually you can get Siplus upto 20A

http://support.automation.siemens.com/WW/view/en/29277158

But since you have already bought the power supplies, I dont see any problem in using the supplies for different sensors.

In fact it is quite common to see mixed supplies across the same card. What you see on many sites is that an estop will kill one power supply that supplies the contactor coils to one section of the plant while another section of the plant continues to run. All you have to keep in mind that your individual cards have IO groupings. for instance the 32 ch standard digital input  card consists of two groups of 16. So the first 16 inputs can have a different supply and 0v reference from the end 16 inputs. So the key is to:

1. Find out the groupings in each card. (could be 4 groups of 8 etc)
2. Stick to the groups and dont cross supplies

So you might be tempted to have functional group supplies instead of just all inputs on one and outputs on th other
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  6/4/2009, 1:21 PM
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Hello,

I like to add little to earlier answers. I think you can use your two power supplies separately if it is possible, (One for CPU supply and inputs, outputs and other for actuators).astonished

Other opting is if you are going to parrell the outputs of the power supplies, you can use protective diodes to prevent reverse power flow.blink

These are only ideas, I don’t no weather they fit with your application. But I hope you they may help.blush

Best regards.


Arunachandra Kariyawasam
Engineer Automation & Drives - Controls Division
Nikini Automation Systems (Pvt) Limited
249, High Level Road, Colombo 05,Sri Lanka.
Tel: +94 (0) 11 2826894
Fax: +94 (0) 11 2826252
Mobile: +94 (0)77 7788677

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  6/5/2009, 6:33 AM
Joined 10/5/2006
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Dear Ayman,Anchobi & Arunakat1,

Thank you very mcuh. I feel very appreciate for all your inputs and ideas!laugh
Thank you and have a happy weekend!laugh

with regards,
how come?
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