Guilhermebr
Electrical
Hello.
Anybody used audio power amplifier for protection relay test?
GS
Anybody used audio power amplifier for protection relay test?
GS
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Audio power amplifier for protection relay test
- Thread starter Guilhermebr
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- #2
Guilhermebr
Electrical
Maybe I have to change the amplifier's internal output transformer, to the current input of the relay, which is almost a short circuit.
The output of the audio amplifier is 2 ohms 250W, and relay current input is <0.02 ohms.
GS
The output of the audio amplifier is 2 ohms 250W, and relay current input is <0.02 ohms.
GS
davidbeach
Electrical
I haven’t really looked into it, but isn’t an audio amplifier a voltage amplifier? Relay testing requires high currents, along with normal and reduced voltages. Pretty sure that if there was an easy out there wouldn’t be nearly so many people buying relay test sets at the prices relay test sets go for.
- Moderator
- #4
The test sets provide an accurate time to trip, which may be lacking in an audio transformer.
Will you add a sine wave generator or scale down grid power for a sine wave input?
Does the amplifier introduce a phase shift?
Some types of protection relays are sensitive to phase angle.
Once you have a suitable transformer, why no just drive the transformer through a ballast resistor with a Variac?
Of course that still leaves the timing issue.
Bill
--------------------
"Why not the best?"
Jimmy Carter
Will you add a sine wave generator or scale down grid power for a sine wave input?
Does the amplifier introduce a phase shift?
Some types of protection relays are sensitive to phase angle.
Once you have a suitable transformer, why no just drive the transformer through a ballast resistor with a Variac?
Of course that still leaves the timing issue.
Bill
--------------------
"Why not the best?"
Jimmy Carter
Dear Mr. Guilhermebr
Q. "...Anybody used audio power amplifier for protection relay test? "
A1. If you check the basic specification of commercial (simple/basic) single-phase relay test sets on the market, in general, having variable ac, dc (voltage) output say 0.01-500V, variable ac, dc (current) output say 0.01-50Adc, 0.01-100Aac. A volt meter, a current meter and a timer say 0.001-9999s. A toggle switch for stopping the timer (time-delay-to-close) or (time-delay-to-open). Some resistors for voltage divider and capacitors for phase-shift applications. More advance types may operate on single-phase input, three-phase output generated internally. These advance types have phase-shift indication with recording features etc....
A2. In general, there is no (audible announcement).
A3. Please advise what is your application and why the use of "audio power amplifier".
Che Kuan Yau (Singapore)
Q. "...Anybody used audio power amplifier for protection relay test? "
A1. If you check the basic specification of commercial (simple/basic) single-phase relay test sets on the market, in general, having variable ac, dc (voltage) output say 0.01-500V, variable ac, dc (current) output say 0.01-50Adc, 0.01-100Aac. A volt meter, a current meter and a timer say 0.001-9999s. A toggle switch for stopping the timer (time-delay-to-close) or (time-delay-to-open). Some resistors for voltage divider and capacitors for phase-shift applications. More advance types may operate on single-phase input, three-phase output generated internally. These advance types have phase-shift indication with recording features etc....
A2. In general, there is no (audible announcement).
A3. Please advise what is your application and why the use of "audio power amplifier".
Che Kuan Yau (Singapore)
- Thread starter
- #6
Guilhermebr
Electrical
Hello.
Normaly for simplie relay 27, 59, 50F, 50N, 51F and 51N protections functions, I use old mono phase source (without amplifier).
When I have complex relay with many protection functions, I rent omicron or similar relay tester.
I Will try audio amplifier becouse is cheppear and its have a good Power, but high voltage for input current relay.
My idea is use signal generator, audio amplifier and transformer for reduced voltage and high current for relay.
GS
Normaly for simplie relay 27, 59, 50F, 50N, 51F and 51N protections functions, I use old mono phase source (without amplifier).
When I have complex relay with many protection functions, I rent omicron or similar relay tester.
I Will try audio amplifier becouse is cheppear and its have a good Power, but high voltage for input current relay.
My idea is use signal generator, audio amplifier and transformer for reduced voltage and high current for relay.
GS
thermionic1
Electrical
If it's the simple relays, perhaps a used commercial test set would be a better choice. I just checked ebay and found
Doble F2000 series $1300.
I have been down similar roads with a self made kit, never an audio amplifier, but a variac, phantom load, etc. I don't miss those days. In my case it may have been because I drove 5 hours and went to use regular kit and it failed. or some special application.
You haven't mentioned a timer, but it was mentioned above and, of course is an important part of the test. You haven't mentioned who owns the relays being tested, but calibration is something else to consider. How are you measuring the output? Are you considering the additive deviations (clamp/shunt + meter, etc).
Most purpose built relay test sets have some degree of safety / overload / open circuit / short circuit protection for these test set and user. If you choose to build your own, consider adding some protection for your ket and yourself.
Doble F2000 series $1300.
I have been down similar roads with a self made kit, never an audio amplifier, but a variac, phantom load, etc. I don't miss those days. In my case it may have been because I drove 5 hours and went to use regular kit and it failed. or some special application.
You haven't mentioned a timer, but it was mentioned above and, of course is an important part of the test. You haven't mentioned who owns the relays being tested, but calibration is something else to consider. How are you measuring the output? Are you considering the additive deviations (clamp/shunt + meter, etc).
Most purpose built relay test sets have some degree of safety / overload / open circuit / short circuit protection for these test set and user. If you choose to build your own, consider adding some protection for your ket and yourself.
- Thread starter
- #9
Guilhermebr
Electrical
Hello Davidbeach
Old audio amplifiers were called voltage amplifiers, and they use a transformer to reduce the voltage and increase the current.
Mosfet amplifiers, also called current amplifiers, have no transformer, so a short on the output goes straight to the mosfet.
I believe that manufacturers of relay testers that use amplifiers have a coupling transformer at the current output.
I don't have much experience with amplifiers, but many manufacturers are using them for electrical testing.
GS
Old audio amplifiers were called voltage amplifiers, and they use a transformer to reduce the voltage and increase the current.
Mosfet amplifiers, also called current amplifiers, have no transformer, so a short on the output goes straight to the mosfet.
I believe that manufacturers of relay testers that use amplifiers have a coupling transformer at the current output.
I don't have much experience with amplifiers, but many manufacturers are using them for electrical testing.
GS
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