SCB 68 maximun voltage and current

[blackbear]

Dear all,

can some 1 tell me whats the maximum voltage and current that my scb 68 for m-series is about the sense?i search the manual but i couldnt find.

cheers
Shawn

[Graziano]

Hi!
   Here, Appendix A, specifications.  Is what you were looking for?

   Anyway, refer to the board's spec, I refer to daq board you're going to use!

graziano

[blackbear]

Hi Grazino

im using this  DAQ model http://sine.ni.com/nips/cds/view/p/lang/en/nid/14132 however the data sheet there wasnt any appendix.
in additon im using scb 68 block. do u noe whats the maximum analog voltage and current signal i can measure?

cheers
shawn

[Graziano]

Hi!
   From this, for PCI-6221,

   Maximum working voltage for analog inputs
(signal + common mode) ................ ±11 V of AI GND

   This is the maximum voltage you have to consider, since Terminal Block can handle 250 Volt, but if you feed you analog in with such a voltage, you'll see some lighting in you lab

   So, short answer: ±11 V of AI GND.

   For current, I've only found Input bias current.............................±100 pA, that's not the maximum current it can handle, of course!

   Please, let me know if I have to be more clear!

graziano

[blackbear]

Dear graziano

thank you for your prompt reply.Actually i am a bit confuse. Should i look out for the max and min voltage and current for SCB 68 block or should i look out for my DAQ M-series card?

also for the current, do u mean 100mA or 100pico A?

[Graziano]

Hi!
   I know you're a little confused

   SCB doesn't have (perhaps I suppose...) electronic components, electronics is on the DAQ board! So you have to check for specifications of the board!
 
   A s I told you, from SCB specs you find that it can handle 250 Volt inputs, but your board, the board connected to the other end, on its analog inputs, supports from -11 Volt to + 11 Volt, referred to ground.  This means that if you connect a 200 Volt signal to your board (through SCB, of course), you will likely damage the board, even if SCB will not be damaged.  Is this clear?

   Carefully read specifications, there you can find many infos! Don't read just datasheets, search for device specifications, and user manuals.

   Anyway, in general, in a system, you should take the most stringent value as maximum rating, so consider this for further analysis.

   I've tryed to make it clear, i hope it is...

   have a nice day, now I'm going out for lunch (in Italy it's 12 o'clock)!

graziano

[blackbear]

Dear graziano

managed to look for the info and the specification at http://www.ni.com/pdf/manuals/371290g.pdf . Btw i was very suprise that it can only measrure a 100pA. what if i have a current of 5A to measure.what should i do?

[Graziano]

Hi!
   No, it isn't this way!  100 pA is a Bias current.  The actual current you can measure will surely be greater than this.  The problem is that I didn't find informations on it. 

   I suppose that you can acquire some tens of mA, or more, but I can't grant this.  I'll search docs a little deeper!

graziano

[Graziano]

---

@blackbear wrote:
what if i have a current of 5A to measure.what should i do?

---

Hi again,
  sorry, I didn't answer! With the board you have, I think the only way of measuring 5 Ampere current, is to do some basic signal conditioning, i.e. you convert current to voltage (remember that your board isn't meant to measure current directly!).  For this you can simply use a measuring resistor (shunt).  If you are not too in touch with HW & electric matters, ask someone to provide this.

   Hope this help!

graziano

[blackbear]

Dear Graziano,

when i am using daq assistant model of labview i realised that the default voltge is -+10 and the current is -+10mA.Do u think its max rating of my daq is -+10mA?