GLOSSARY

Analog Panel Meter

Any measuring device that can be mounted in a panel and has an indicating pointer such as the hands on a watch, but in most cases has only one hand, or "indicating pointer". 

Physical Size

General terms referring to the size of these panel meters are referenced as 1 1/2", 2 1/2", 3 1/2", etc.  This is only a general size.  Detailed information on exact dimensions are listed in the manufacturer's catalogs.  For the most part these sizes are an industry standard and the meters are usually categorize by size.  So when we ask a customer "What size meter are you looking for?"  they may reply "3 1/2".  Three and a half inches is one of the most common.

Input

An input or signal is the force that the pointer reacts to. It is applied to the terminals on the panel meter.  So when we ask the customer what is the input for this meter their response could be a variety of "inputs" or "signals."  Not all but some of the most common are:  0-5 AC Amperes, 0-150 AC Volts, 0-300 AC Volts, 0-600 AC Volts, 0-50 Millivolts DC, 0-10 VDC, 0-100 DC Volts, 4-20 Milliamperes DC, 1-5 DC Volts, 55-65 Hertz, etc.  In the lab we also refer to this input as "Full Scale" or "End Scale" (not to be confused with the "scale").  It's also critical that when we request these inputs from the customer that they be expressed in "AC" or "DC" whenever possible.  AC and DC are two different animals.  If a customer specifies a "0-5 Amp" meter with a "0-5 Amp input" and a "0-5 Amp scale" we need to verify not assume AC or DC.

Scale or Dial

An input is applied and the pointer begins to move (we call this "pointer deflection" or "traveling up scale").  In order to "measure" the distance or measure the input,  a scale or dial lays just underneath the pointer with lines or "divisions".  These divisions are numbered and usually in the center under the divisions and numbers is the caption.  Similar to my speedometer on my truck (mines an older truck so it's not digital),  but the principle is the same.  The scale has numbers on it  so it lets me know how fast I'm traveling when I speed up or slow down, the caption is MPH. The pointer lets me know when I'm at the safe operating speed of 100 mph for I-285 here in Atlanta.  So we may ask our customer "what do you need the scale to be".  It's common for the input to be one thing and the scale to be another.  More specifically is a CT (current transformer) rated meter.  Lets take a 250340LSPK (this is a CT rated meter).  This meter has an input of 0-5 AC Amps and a scale of 0-100 AC Amps. As with the "input"  if AC or DC is not originally specified we also need to verify the scale or caption as AC or DC.  Commonly a CT rated meter as in the case above would be "AC" or "AC Amperes" (in this case AC Amperes is the caption).

Caption

On the scale are divisions and the divisions are numbered accordingly.  The caption usually indicates specifically what the panel meter is measuring.  Captions can be absolutely anything.  A customer may have an application where the "input" is 0-10 AC Volts and the "scale" may be 0-1000 with a caption of RPM.  Some other common examples are YPM (yard per minute), FPM (feet per minute), Tow Speed, Percent, etc.  Many more can be found on the "Summary of Lab Capabilities" in the section marked as "Engineering Units that can be displayed".

Full Scale

If we relate this to your gas gauge on your automobile, what does it take to make your gas gauge read a full tank or what does it take to make it read "full scale"?  A full tank of gas means your gas gauge or meter is reading the maximum it can read, a full tank or "full scale."  Same for a panel meter, what input or signal does the meter require to make the pointer move to it's maximum point or full scale.  So our question to the customer would be "Do you know what the input is, or what is the full scale for the meter?"  Look out, because some customers will refer to the "scale" as "full scale."  That's why we ask for both input and scale to the meter.

End Scale

Similar to full scale but different.  End scale commonly refers to a meter that reads DC.  Let's take, for example, a battery.  There is a positive and negative terminal.  If I hook this battery up correctly to a DC Voltmeter, the pointer will read "up scale," commonly the pointer will move to the right.  If I reverse the hook up or switch the wires to the two terminals on the voltmeter the meter will read to the left.  Many times a customer will want to see the pointer move (called pointer defection) to the right and to the left.  Depending on their application they want to measure negative and positive.  So they would require a meter to read minus and positive.  Without any input or signal applied to the meter, the pointer rests in the center marked as "0."  Now we have a meter that reads to left and to the right with "0" in the center.  Let's say the meter at the maximum will indicate 10 Volts DC to the left and 10 Volts DC to the right (in most cases both left and right values are the same).  We call this "End Scale" or the meter has an "End Scale of 10 Volts DC."  When we refer to "end scale"  we're talking about a  "zero centered meter."  So in the example above we could have a "End Scale of 10 VDC " or a "Full Scale of 10 - 0 - 10 VDC."  Both are correct.

Terminals

Most of the basic panel meters have two terminals or studs (not to be confused with "mounting studs") on the back of the meter.  This is where this input or signal is applied.  The size and makeup of the terminals vary with manufacturer and input.  One of the most common uses of the word terminal is "terminal resistance."  This is the total amount of resistance the meter has.  It's measured from one terminal to the other and is indicated in "ohms" or resistance.  Many manufacturer's list "terminal resistance" in their catalogs or technical data.

Now you can begin to understand what basic information is required to "build" a part number. As we construct a analog panel meter from scratch, some of the key questions are size, input & scale.

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