What is "Infinite Resistance"?

[greener]

I am working with a specification that states "Infinite Resistance" between all non-ground pins of a connector and the ground plane. What can I use as the practical limit for measurement using standard equipment and practical as far as standard practices?

Circuit is 28V Nominal DC. (12-32VDC)

 

[buzzp]

They want total isolation. Measure with standard ohmmeter/multimeter and if it says 'OL' for over limit or whatever then this is likely acceptable for most applications. If you wanted you could measure this with a hi-pot tester but it would likely damage components and should be considered a destructive test for PCB's. The hi-pot tester would indicate a current leakage and you would know the applied voltage so you could calculate the resistance or some hi-pot testers will show resistance. I am sure this is not necessary in your situation. Good luck

 

[greener]

Currently I am getting readings in the high mega-ohm range of my multimeter. If I use other multimeters I get the "OL".

I was wondering if there was a generally accepted definition of "Infinite"

 

[nbucska]

Is the spec's related to the connector ?

For a connector -- unless it is some special appl.
e.g. charge amplifier input -- many megohms is
for all practical purpose infinite.

It would help is we knew if the connector is input or output and what kind of circuits.


<nbucska@pcperipherals.com>

 

[greener]

Connector is a Mil Std D38999 connector.
The circuit is a timer/driver circuit for solenoids.
DC voltage 16-32 V. Max current 2 amp.

 

[nbucska]

If R>>10 Mohm, OK.( Connector alone, with circuits disconnected) <nbucska@pcperipherals.com>

 

[greener]

How did you get R>>10 Mohm as the answer?

 

[nbucska]

Out of the thin air with 30+ years of experience :

On the output side there is no problem: A few KOhm would
be good enough i.e wet cardboard would be acceptable
insulator.

I assume there is no some specially sensitive circuit
for you would have said so.

The timer must have some trigger input. The input may be
driven by a circuit or switch. A switch is very seldom
operated with very low current.

If the connector is disconnected, the circuit doesn't have
to work; the only problem is safety.

If the circuit is bipolar, a few MOhm is acceptable. Unprotected CMOS input is unlikelly since it would be too sensitive for static.
<nbucska@pcperipherals.com>

 

[buzzp]

It sounds like what your measuring is the resistance between parts of the circuitry if you are measuring from 'ground' and a pin on the connector. If this is the case, then you should not measure any resistance if the test specifications say infinite. I would consult whomever wrote the procedure and ask them exactly what they meant by infinite. Are you indeed measuring between a pin that goes to the same PCB that the ground plane is on? If your working with solenoids, then the small signal circuitry is likely isolated in some way from the coil on the solenoid.

 

[jbartos]

Suggestion: Normally, the infinite resistance is characterized by an open circuit. If you use meters, then apply relativity reasoning and comparison reasoning, e.g. in connector pin applications. The ohmeter will read the largest resistance on an suitably selected ohmeter range, which is also relative since what is in one case an open circuit characterized by the largest resistance, in the other case is still not the resistance value large enough. If you work with mil specs, there will be some values of resistence or resistance inequalities stated as acceptable.

 

fd