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VR6 caterpillar voltage regulator... 5
- Thread starter emiluz
- Start date
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- #2
catserveng
Electrical
CAT does not put service info out for "free". You need to contact the dealer you bought the part from. There is a set of instructions to convert a unit from a VR3 to a VR6 regulator.
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GenSwgrEng
Electrical
Try this URL:
Engineers are always honest in matters of technology and human relationships. That's why it's a good idea to keep engineers away from customers, romantic interests, and other people who can't handle the truth.
http://www.cat.com/cda/components/securedFile/displaySecuredFileServletJSP?fileId=92965&languageId=7
Engineers are always honest in matters of technology and human relationships. That's why it's a good idea to keep engineers away from customers, romantic interests, and other people who can't handle the truth.
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2
- Thread starter
- #4
tnx genSwgEng...its a good help,is there a way I can use it in replacement of my old VR3....the sensing voltage is diferent, but I believe CAt does not have the VR3 on their stock thats why they gave me VR6 instead...thanks again man for the sensible reply
catserveng
Electrical
This is a link to KATO for a similar regulator,
note this manual provides information that does not include the VR6, mainly in the different voltage sensing ranges.
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.
note this manual provides information that does not include the VR6, mainly in the different voltage sensing ranges.
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.
- Thread starter
- #6
what capacity of PT should I use for my VR6? If my computation serves me right, my sensing voltage fuse rating is 10 amps, and the sensing voltage is 480, does that mean that I have to use 5KVA or more PT?
Anybody knows where can I purchase a replacement for my VR3 here in the philippines.
Anybody knows where can I purchase a replacement for my VR3 here in the philippines.
catserveng
Electrical
The best aftermarker replacement for a CAT VR3 is a Basler AVC63-12, they offer several different sensing voltage ranges.
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.
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.
emiluz, procurement of such components you're looking is somewhat tiresome.
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.
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.
- Thread starter
- #9
emiluz
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*
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*
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- Moderator
- #11
The PMG gives you less voltage dip under block loading and motor starting and also higher short circuit current. A PMG also avoids voltage collapse.
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
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
- Thread starter
- #12
I got a brand new VR3 voltage regulator,but when I installed it,there is no output on the terminal for the excitation voltage. the technician said that it could be a problem with my excitation field winding....is that posible...I was just wondering, the excitation ouput is an output from the regulator itself, how come that the technician is saying that the problem is with my winding?
How does the pmg voltage, related to the sensing voltage?where does the AVR get its supply, from the PMG or the sensing voltage?
How does the pmg voltage, related to the sensing voltage?where does the AVR get its supply, from the PMG or the sensing voltage?
catserveng
Electrical
VR3 regulators come in two basic styles, PM and SE. Since it appears you have a PM system, the CAT Generator PM puts out 100 VAC at about 240 Hz. The PM comes in on terminals 26, 28 and 30 of the VR3. There are two kinds of fuses CAT put in the PM circuit depending on vintage of your machine, there ar two in line fuse holders on older machines, and newer machnines have two terminal block fuses using a miniature fuse.
The typical excitor stator winding resistance is about 4 ohms, so measure between F1 and F2 to see if you have the field.
The typical excitor stator winding resistance is about 4 ohms, so measure between F1 and F2 to see if you have the field.
- Thread starter
- #14
Im a bit confused, how come the technician came to the conclusion that the exciter field winding is defective. How do I know if its really defective or not aside from measuring its resistance. my main problem is, all the wiring was installed including the PMG but the technician told me that the output of the F1 F2 is 35V which he mentioned as higher that the usual @ no load. is there a way that the output of the exciter voltage from the AVR be asjusted to meet the desired value?
catserveng
Electrical
Maybe we should try to make some definitions, since there seems to be a bit of confusion, at least from my standpoint.
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,
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,
- Thread starter
- #17
is it ok to use CPT for instead of a PT to convert the sensing to the rated voltage of the AVR?
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.
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.
- Thread starter
- #18
without connection to the CT and the external droop adjustment, and the only terminals connected are the PMG, and sensing voltage.
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....
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....
- Thread starter
- #19
I have a new findings...
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?
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?
catserveng
Electrical
Based on the info provided above, you are putting excitation voltage to the excitor styator, but only measuring residual voltage at the field terminals.
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.
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.
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