[volt-nuts] Fluke 5100B Calibrator‏ Repair Help

[David McQuate]

Estimate the steady-state maximum current (eg from the unit's normal 
mains current) then search Digikey for "inrush current limiters".  
Select  values near or a little greater than your estimated mains 
current in the 6th list-box (select multiple values), titled "Current - 
Steady State Max", and click "Apply Filters".

Also make a guess as to the allowable voltage drop across the varistors 
in steady state operation.  Divide by the estimated current and select a 
similar or lower value in the 7th listbox, and again click "Apply 
Filters".  That should leave you with a managable number of parts to 
look thru in the table at the bottom of the web page.

Look at the R at 25C, which will be the major factor in limiting inrush 
current.  I would tend to choose a varistor with the largest R25, for 
minimum inrush current.

(I have no pecuniary interest in Digikey, but I've been a long-term 
customer, and I think their search capability is so much better than any 
others.)

I hope you find this useful.  Feel free to email.

Dave

On 3/13/2014 8:34 AM, David Smith wrote:
> I need some help with repairing a Fluke 5100B Calibrator.
> The capacitor support bracket fell into the power supply module and vaporized both varistors, RV1 and RV2. A call to Fluke tells me they no longer can supply these MOV's. According to the manual's parts list these varistors are in-house parts by Fluke. I have no way of determining a substitute part. Is there anyone that can help me identify what could be a useful replacement?
> Thanks,
> Dave - W6TE 		 	   		
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