The 'maximum working [insulation] EMF' of D'arsonval units should be specified in the manufacturer's literature...Hello, I've some question regarding the Rated Voltage on Ammeter.
How can I know what is the Rated Voltage from the existing Ammeter? Do it have a Label? Or we can measure it?
I've attached the photo of my existing Ammeter.
View attachment 86309
Thanks.
Thanks for the reply, the meter is already 20 Years old back. Sad that, I can't get anything from the manufacturer.The 'maximum working [insulation] EMF' of D'arsonval units should be specified in the manufacturer's literature...
Best regards
HP
As I know that DC ammeter should have 2 lines with one of it is doted and parallel to each other. I guess the symbol at the left bottom shows it's DC ammeter, am I right?If that is a DC ammeter, measure the resistance of the meter. That and Ohm's law gives you the maximum working voltage.
ak
That, and the FS current indication, would allow calculation of the full scale deflection 'voltage' drop (IOW the maximum terminal-to-terminal EMF)--- It is my impression, however, that the OP wishes to determine the insulation strength (i.e. the maximum EMF at which the instrument may be safely operated above chassis/environmental ground)...?If that is a DC ammeter, measure the resistance of the meter. That and Ohm's law gives you the maximum working voltage.
ak
Polarity symbols (i.e. "+" and "-") on or near the terminal posts would suggest that the instrument is indeed a DC indicator, however absence of same does not necessary mean otherwise...As I know that DC ammeter should have 2 lines with one of it is doted and parallel to each other. I guess the symbol at the left bottom shows it's DC ammeter, am I right?
That is typically not a useful parameter, thus it's usually not specified. You should only connect a current to your meter, hopefully a current that's equal to or less than the max reading. Voltage will take care of itself.Hello, I've some question regarding the Rated Voltage on Ammeter.
How can I know what is the Rated Voltage from the existing Ammeter? Do it have a Label? Or we can measure it?
Thanks.
While I agree that knowledge of E(full swing) is of little value (save for calculating shunt parameters) -- Insulation 'voltage' is an important consideration in applications 'floating' the meter above Ca. 100v As, for instance, monitoring current drawn from the B+ rail in 'electron tube' equipment, etc...That is typically not a useful parameter, thus it's usually not specified. You should only connect a current to your meter, hopefully a current that's equal to or less than the max reading. Voltage will take care of itself.
Rated Voltage: Just like the question above, is that 220V or 440V will be very much different for ammeter?
Thanks for the reply,Unless you will be purchasing/fabricating shunt{s}, the sole significance of 'voltage' is the meter's insulation rating (Spec. maximum allowable potential difference 'metered line' to chassis/ground) - probably not an issue in your application --- The 'voltage' across the meter is determined by the current through, and internal resistance of, same and need not be considered, unless, again, you need to calculate shunt resistance...
Best regards
HP
Yes, an ammeter rated at (i.e. insulated to) 440 volts is applicable to lower EMFs -- One caveat though, 220v and 440v are standard 'mains' (and, hence, AC) EMFs -- But your previous posts seem to indicate you require a DC ammeter -- Are you certain the instrument under consideration is applicable to your application?Thanks for the reply,
If I choose the higher rated voltage eg: 440V Ammeter, is that the 440V ammeter can be use for 220V circuit too? As I think it's the maximum allowable voltage, which suppose to be fine if I use higher rated Ammeter (440V) in the same or lower voltage (440V/220V) circuit right?
AFAICR: there were 2 standard voltages for those meters, you had to check which you had before ordering shunts.The 'maximum working [insulation] EMF' of D'arsonval units should be specified in the manufacturer's literature...
Best regards
HP
A quick search on Wiki came up with 75mV and 100mV.AFAICR: there were 2 standard voltages for those meters, you had to check which you had before ordering shunts.
AFAICR: there were 2 standard voltages for those meters, you had to check which you had before ordering shunts.
...As opposed to 220V and 440V which is why I maintain that the specification in question is that of maximum working case insulation EMFA quick search on Wiki came up with 75mV and 100mV.
Seems I overlooked that bit of the original question, somehow I just never seemed to have bothered checking insulation rating of meters, maybe because I rarely operated them on mains potential lines....As opposed to 220V and 440V which is why I maintain that the specification in question is that of maximum working case insulation EMF
Best regards
HP
1. I think the symbol shown in the 1st image is DC Right?Yes, an ammeter rated at (i.e. insulated to) 440 volts is applicable to lower EMFs -- One caveat though, 220v and 440v are standard 'mains' (and, hence, AC) EMFs -- But your previous posts seem to indicate you require a DC ammeter -- Are you certain the instrument under consideration is applicable to your application?
While not impossible, I think it unlikely that DC instruments would be 'specified' at common AC values... Just my $0.02
Best regards
HP
1) No -- I do not regard a pentagram-bound '3' as indicative of DC operation -- however, based upon the image attached to post #11, I feel the instrument is, indeed, a DC indicator...1. I think the symbol shown in the 1st image is DC Right?
2. If that is DC ammeter, I think you are right, it should not have such rating on 220V or 440V which is AC right?
Thanks
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