VR6 caterpillar voltage regulator...
VR6 caterpillar voltage regulator...
(OP)
where can I download installation diagram of my VR6. We used to have VR3, there are some terminal tags that doesnt mach the VR6....please help me.
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VR6 caterpillar voltage regulator...
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VR6 caterpillar voltage regulator...VR6 caterpillar voltage regulator...(OP)
where can I download installation diagram of my VR6. We used to have VR3, there are some terminal tags that doesnt mach the VR6....please help me.
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RE: VR6 caterpillar voltage regulator...
RE: VR6 caterpillar voltage regulator...
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RE: VR6 caterpillar voltage regulator...
RE: VR6 caterpillar voltage regulator...
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The sales literature from the other link does not give you the phase relationship for the voltage sensing. Based on that info it appears that 20 is A phase, 22 is B phase and 24 is C phase, this is NOT correct, A phase is 22, B phase is 24, and C phase is 20. If you have a standalone unit with no droop CT, this is not much of an issue, except that it can affect stability, if you parallel the unit with either the grid or other generators, then this becomes important. The VR3 has been discontinued and the VR6 is the replacement. Depending on your application it can be a simple change over or may require a different droop CT and wiring changes. CAT has a published Special Instruction that can help you determine what you'll need to do, the dealer that sold you the part should be able to provide a copy for you. The instruction publication number is REHS2505, and the manual for the regulator is RENR2480. The parts man at the counter can probably print you a copy off the on-line system. Currently the VR6 is only supplied for 240 VAC sensing, so again, you may have to add PT's or connect to the center tap leads (if supplied) depending on your original installation.
RE: VR6 caterpillar voltage regulator...
Anybody knows where can I purchase a replacement for my VR3 here in the philippines.
RE: VR6 caterpillar voltage regulator...
Both the VR3 and the VR6 (and the Basler and Kato versions) have a power input burden of about 1100VA, and the sensing burden is less than 1 VA.
The Basler SSR 65-12 has also been used succesfully to replace a CAT regulator, except the PM versions are a little underpowered since the CAT PM is three phase, and to use it on the Basler SSR you hook it up single phase. If you don't have a big motor starting requirement of need full forcing in a fault they have worked quite well.
There are probably other manufacturers of AVR's out there, the nominal output of the CAT AVR is 65 VDC at 12 amps into a nominal 4 ohm field. If you are using a PM generator, the nominal output is 100 volts at 240 Hz.
RE: VR6 caterpillar voltage regulator...
I had known a service provider, locally available, who works on CAT generator control and protection. Obviously, this CAT controls comes with the generator control and generator itself ,OEM usually Marathon Electric and comes with BASLER (for cotrols and protection). They works also with woodward.
Where is your location in Phils?
Regards,
"Whenever you are asked if you can do a job, tell them, certainly I can! Then get busy and find out how to do it." Theodore Roosevelt.
RE: VR6 caterpillar voltage regulator...
RE: VR6 caterpillar voltage regulator...
I am right now at a site where 2 x 15 MW, 6.6 KV TG sets (3000 & 1500 RPM) are working well with non-oem avr's for past two years. They use PT's instead of PMG for voltage sensing. They operate on 220 V DC, which is anyway there for protection circuits.
Problem with OEM avr's is that their service is non-existent or comes at a high cost to justify other options.
So, in your case, if the avr supplier has a good track record, go for it.
*Nothing exists except atoms and empty space; everything else is just an opinion*
RE: VR6 caterpillar voltage regulator...
I have replaced PMG regulators with conventional regulators to maintain service while we were waiting for the PMG regulator to arrive.
One issue to be aware of if your set(s) are large, over 1000KVA, is proper protection. In the event of a fault on the system the Non-PMG AVR may not provide enough current to reach the trip settings of the protection system. You may have objectionable voltage dip when starting large motors with a Non-PMG AVR.
respectfully
RE: VR6 caterpillar voltage regulator...
How does the pmg voltage, related to the sensing voltage?where does the AVR get its supply, from the PMG or the sensing voltage?
RE: VR6 caterpillar voltage regulator...
The typical excitor stator winding resistance is about 4 ohms, so measure between F1 and F2 to see if you have the field.
RE: VR6 caterpillar voltage regulator...
RE: VR6 caterpillar voltage regulator...
F1 and F2 are the output to the pilot excitor (what some people call the excitation output).
The power for the AVR on a PM type generator comes into terms 26, 28, and 30 from the permanent magnet generator thru two fuses. It is nominal 100 VAC at 240 Hz
The sensing comes in on terminals 20, 22, and 24.
The droop CT (if installed)is on terminals 6 (Polarity) and 5 (Common)
The remote voltage adjust if installed is between terminals 4 and 7.
You said the technician measures 35 volts (DC?) at F1 and F2, yes this is higher than expected, normal no load field output is about 10-15 VDC at about 2 amps DC. What is the voltage at the generator terminals and at the sensing input of the AVR (terms 20, 22, 24)? With the engine at rated speed, what is the voltage at the power input terminals, 26, 28, 30?
The excitor stator can be tested by checking the resistance, and by meggger testing at 250 VDC, should be at least 10 Mohms to ground.
Have the diodes been tested? And what is the condition of the rotating rectifier surge suppresor?
Do you have PT's on the sensing inputs to the AVR? Or is the sensing directly connected to the generator terminals? When you measure sensing, make sure you measure 20-22, 22-24, and 24-20, make sure you have all three phases, same with the PM input, 26-28, 28-30, 30-26.
If your AVR output at F1 and F2 is high, and you're not reaching rated voltage at the generator terminals, it could be a bad excitor stator (field), excitor rotor, problem in the rotating rectifier assembly, a problem in the main rotor, or a problem in the stator.
Hope that helps,
RE: VR6 caterpillar voltage regulator...
A LPS for you.
*Nothing exists except atoms and empty space; everything else is just an opinion*
RE: VR6 caterpillar voltage regulator...
I encountered a problem recently upon testing of one of the service unit provided by the contractor.
case 1.
Its a VR6 I think, so they use a CPT instead of PT to step down the voltage to 240V. The genset worked but the voltage is too high, the speed is normal since the frequency is stable to 60 Hz at rated speed. they tried adjusting the trimmer for voltage control but didnt work.
case 2.
they installed a VR3, and used their CPT again.when we tried to start the gen, it genearates voltage for several seconds, but collapsed.
what could be the source of such cases?
tnx.
RE: VR6 caterpillar voltage regulator...
results and output.
1. Voltage across terminals of the PMG(AVR terminals) is 91,91.3,91.1 Vac respectively.
2. Voltage across termina(AVR Terminals)is of the sensing are 12.5, 12.5, 12.8 Vac respectively.
3. measuring across F1, F2, 45 Vdc.
Its unsusual right?
please help....
RE: VR6 caterpillar voltage regulator...
I have compared the output of our other genset to the defective one, and notice that when the exciter fied winding is not connected to the F1 and F2 terminals, it normally measures 35 Vdc, but when I connect the leads to the terminal, the voltage is generated and later collapsed, and observered the input voltage from the sensing to be low and unbalanced? the voltage reaches as low as 35, 25, 15 Vac. could be a problem with our generator windings?
RE: VR6 caterpillar voltage regulator...
What is odd is that the excitation output is only going to 45 volts, as with the available voltage the AVR should be putting out 65 VDC to the excitor field. Do you have a way to measure the DC current to the field? It is about 10-12 amps at full load.
Now you need to measure the excitor stator resistance, and megger test it, as it sounds like based on the info provided you have an excitor stator pulling down the AVR output.
Excitor stator faiilures are rare, but not unheard of. While you have it down, please go ahead and check the diodes and surge suppressor, and megger test the rest of the excitor and rotor components.
Since you are using PT's for the sensing, did you measure at the generator terminals and at the AVR sensing inputs, and assure that you are not seeing an inaccurate sensing issue?
Normally we don't use what the industry terms a CPT as it is designed to provide control power, not a precise voltage in proportion to the high side voltage. My experience is that CPT's have a fairly wide variation in secondary versus primary voltage, as thier primary goal is to provide control power. Maybe some others viewing this forum would care to comment on that?
You mention above that is makes voltage for several seconds then "collapses", is the voltage reading above the value before or after it "collapses". The VR3 has an internal thermal limiter that will shutoff excitation if the field current exceeds 12 amps for about 10-15 seconds. Does this sound like the amount of time it builds voltage and then drops to residual?
Get a second meter and measure at the generator terminals before the CPT's you are using. Also, how are the CPT's connected? are there three connected wye or two connected open delta?
Based on the info above regarding the VR6 and the VR3, it sounds like you may have a sensing problem, coupled with an excitor field that may be slightly out of tolerance for resistance.
RE: VR6 caterpillar voltage regulator...
1. When the exciter stator is not connected to the F1, F2 the sensing voltage terminals reads... up to 12Vac, and the F1 F2 reads....48Vdc.
2. When I connect the exciter stator to F1 F2, the generator starts to build up voltage and goes as hig as 600 Vac. During these stage measuring the sensing voltage terminal it reads...an unbalance 25, 35, 15 Vac. and F1 F2 terminals reads...80Vdc.
It seems that I am getting a 600 Vac from the terminals of the generator, but I have an unbalance low sensing voltage input on my AVR.
RE: VR6 caterpillar voltage regulator...
1. I never had a chance to measure the voltage before the CPT.the 600Vac that I was talking about is the voltage being displayed in the output voltage of the generator pannel.
2. We used 2 CPT connected open delta. and the unbalance low voltage that I am talking about is the voltage across the sensing leads, connected to the AVR's sensing voltage terminals.
RE: VR6 caterpillar voltage regulator...
On the face of the VR3 there is a tag with its part number, and sensing voltage rating. You need an appropriate set of open delta PT's (CAT's standard connection) to take the generator terminal voltage and step it down to the sensing voltage so the system will work correctly. Typical CAT application is 480 to 240 VAC PT's, but there are other possible configurations.
It appears you have started another thread to test the rectifier and surge suppresor, you really need to get a copy of the service manual for this generator if you are going to work on this yourself, it is CAT publication number SENR5359.
RE: VR6 caterpillar voltage regulator...