If all of the smaller MEPs use a similar method of running the frequency meter then maybe anyone can help. Please chime in. MEP 002 and 003 panels look the same as my 016B.
One of my 016B's has decided to challenge my knowledge of the frequency meter system.
I've had the gen a few months and have ran it and load tested and sorted a few other minor details. All good.
Well the other day I did a cold start at about 45 degrees and it took right off with no preheat. I usually leave the throttle in the normal running position when I hit the shutdown switch. Therefore it is already set when warmed up.
So I was surprised to see the freq meter peg at 65 with a cold engine.
I don't have a freq test meter yet but I will get one. Meanwhile I started my second set put it on 60hz and then adjusted the first set until the drone was very slowly going in and out liking synching engines on a twin aircraft.
The meter on the first set eventually krept down to about 63hz when the unit warmed up with load and after I turned the cal screw on the face of the meter which was good for about 1hz of movement.
The manual shows an adjsutment screw on the transducer but I have not had the chance to mess with it.
The meter is the old style Ideal Precision brand. Any suggestions as to why this happened? Is this a typical problem? Any fixes better than using original parts? Like a replacement meter that picks up direct off of the 120VAC outlet feed in the panel and avoids the transducer?
Digital meters can be picky, they read fine without a load but put anything other than pure resistive on them and they don't seem to deal with the back EMF.
The adjusting screw is the bias screw, it should only be moved with known frequency. It affects the entire scale. Basically, the frequency transducer generates a tiny current which is proportional to frequency. The meter's needle is connected to an electromagnet which forces against a set of tiny springs. The torque is proportional to current, same with the resultant torque of the springs. That screw adjusts the spring.
Yes, some transducers have adjustments. These should only be adjusted with an accurate meter. And some transducers can be plugged into utility power which is a good frequency reference, being between 59.9 and 60.1 Hz under normal conditions.
Finally, IF you are brave, you could use the two lightbulb method to use utility power as a reference. The bulbs flash when out of sync with mains. Being a tiny load, it is generally safe. And this is how the power unit trailer transfer switches twin lights worked.
Digital meters can be picky, they read fine without a load but put anything other than pure resistive on them and they don't seem to deal with the back EMF.
The adjusting screw is the bias screw, it should only be moved with known frequency. It affects the entire scale. Basically, the frequency transducer generates a tiny current which is proportional to frequency. The meter's needle is connected to an electromagnet which forces against a set of tiny springs. The torque is proportional to current, same with the resultant torque of the springs. That screw adjusts the spring.
Yes, some transducers have adjustments. These should only be adjusted with an accurate meter. And some transducers can be plugged into utility power which is a good frequency reference, being between 59.9 and 60.1 Hz under normal conditions.
Finally, IF you are brave, you could use the two lightbulb method to use utility power as a reference. The bulbs flash when out of sync with mains. Being a tiny load, it is generally safe. And this is how the power unit trailer transfer switches twin lights worked.
Keith,
I was thinking of getting a freq meter anyway. Someone said the Kill a watt plug in measuring device is $25 and has freq display. Accuracy?? Multimeters with freq are around $90 and up at Home Depot.
The Freq transducer takes a two wire input off of the convenience outlet which is directly tied to the T1-T4 winding.
So what do you think about the idea of disconnecting the supply from the freq transducer and connecting household 120VAC to supply it and calibrate the meter against the measured household freq? It appears that the freq input and meter output and meter itself are totally divorced from any other generator connections, components, or wires (so no harm to anything else?) To be totally safe I could disconnect all transducer and meter wires and run new jumpers to the transducer and meter just for the household test.
Get the Kill-A-Watt (make sure it is the basic model P4400, as some of the fancier ones that calculate electricity cost do not have the freq meter) they are handy to have around and do a good job on reading frequency from generators, many cheaper multimeters will give false readings on generators due to the wave form, I have one "cheap" $50 multimeter that reads about triple the actual frequency when connected to a generator, I also have a Fluke 87V that gets it right every time, but it does also MSRP for over $400 (I paid $120 or so used on ebay).
Sorry wish i know more about MEPs, i have painted a few MEP 12`s just this month but i dont get to work on them. Good luck! need anyone to paint it im your man lol
I usually leave the throttle in the normal running position when I hit the shutdown switch. Therefore it is already set when warmed up...
Usually or always? I understand once you get the throttle set where it belongs, you leave it there.
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Yes, always leave throttle (governor speed control) at 60 Hz. The voltage regulator lasts longer that way.
The basic Kill-O-Watt meters work well enough and are somewhat immune to back EMF (reactive current) which throws off meters.
Using utility current to calibrate the transducer and meter is a good idea, as long as you are certain the transducer is running off one of the windings. Since nearly all MEPs for AC are based on multiples of 120 volts, meaning each output winding is 120 volts. If using utility current, make it safe by insulating the 120 volt terminals. And never short the output, the electronics don't like that.
Get the Kill-A-Watt (make sure it is the basic model P4400, as some of the fancier ones that calculate electricity cost do not have the freq meter) they are handy to have around and do a good job on reading frequency from generators, many cheaper multimeters will give false readings on generators due to the wave form, I have one "cheap" $50 multimeter that reads about triple the actual frequency when connected to a generator, I also have a Fluke 87V that gets it right every time, but it does also MSRP for over $400 (I paid $120 or so used on ebay).
Ike
Great info. I'm on the hunt for a p4400. I think camping world has them. I like the wattmeter too as it will be useful for both camper and generator!
Usually or always? I understand once you get the throttle set where it belongs, you leave it there.
Yes I read about the voltage regulator not liking off scale frequencies. I totally set up my fuel governing system on both units to include lowest hand knob set point at low idle no load = 55 hz high idle no load = 65hz.
I do fine adjustment because I'm an anal nerdy engineer by degree each time I have a steady load. But yes, now, I always leave the hand knob as is when I shut down. I hope 55 to 65 is not a problem for the VR.
Yes, always leave throttle (governor speed control) at 60 Hz. The voltage regulator lasts longer that way.
The basic Kill-O-Watt meters work well enough and are somewhat immune to back EMF (reactive current) which throws off meters.
Using utility current to calibrate the transducer and meter is a good idea, as long as you are certain the transducer is running off one of the windings. Since nearly all MEPs for AC are based on multiples of 120 volts, meaning each output winding is 120 volts. If using utility current, make it safe by insulating the 120 volt terminals. And never short the output, the electronics don't like that.
Okay, then I have my assignment! 1. Buy a Kill a Watt. 2. conduct calibration with 120VAC household. I did just read the big "Frequency Meter and Transducer" thread and gained valuable info. while you were preparing your reply! Thanks for that info too. Thanks to everyone. I'm going to reset the meter needle bias to a midpoint and hopefully just calibrate the transducer to get the meter accuracy restored. If not, then I'm back to the big thread to re-read the transducer testing methods!
MEP Frequency Meter is Funny
