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AC Voltage Regulators

M

Myauk

Jan 1, 1970
0
In my country, I took part in design and construction of Auto
Transformer AC Voltage Regulators with automatic control of tap
changing with electromechanical relays.

Since my country is less developing country in Electrical and
Electronics product development, I would like to know if these
Electromechanical Relay Type-Automativ AC Voltage Regulators with Auto
Transformers are obselete or not.

Are they still required for certain applications?

If it is not useful anymore, I would study
solid-state-relay-auto-transformer type regulators, and PWM control
type, Servo motor control type AC regulator designs!

More over I would like to know how to study and analyze relay
connection scheme for such regulators. ( I mean we use up to five SPDT
relays to change six different tapping for auto-transformer to provide
six different turn ratios, one step down, five step up between the ac
input and output. I would like to study different combinations of relay
contact points to provide a good voltage regulation scheme)
 
K

Ken Smith

Jan 1, 1970
0
In my country, I took part in design and construction of Auto
Transformer AC Voltage Regulators with automatic control of tap
changing with electromechanical relays.

Since my country is less developing country in Electrical and
Electronics product development, I would like to know if these
Electromechanical Relay Type-Automativ AC Voltage Regulators with Auto
Transformers are obselete or not.

They also make electro-mechanical ones that don't use relays. These may
be a better thing for you to think about. Imagine an object that looks
mechanically like an AC motor.

The stator is much as you would expect in the AC motor.

The rotor has a winding on it that is only part of the secondary turns.

If you imagine the stator and rotor windings connected in series, you will
see how turning the shaft will vary the turns ratio from less than 1:1 to
more than 1:1.

To remove the leakage inductance, a heavy copper strap is used to act as a
shorted turn to the leakage.

Ones like these are still in use here and there in China. They are
extremely robust but they don't remove sudden pulses of power. They are
still worth knowing about because the theory they work on may be adapted
to something more modern.


All such devices make matters worse for others. When the mains voltage is
low, they draw more current and when it goes high they draw less current.
This makes the variations worse. For this reason, they con only be used
on a small fraction of the loads if you want the power system to be
stable.
 
M

Michael A. Terrell

Jan 1, 1970
0
Myauk said:
In my country, I took part in design and construction of Auto
Transformer AC Voltage Regulators with automatic control of tap
changing with electromechanical relays.

Since my country is less developing country in Electrical and
Electronics product development, I would like to know if these
Electromechanical Relay Type-Automativ AC Voltage Regulators with Auto
Transformers are obselete or not.

Are they still required for certain applications?

If it is not useful anymore, I would study
solid-state-relay-auto-transformer type regulators, and PWM control
type, Servo motor control type AC regulator designs!

More over I would like to know how to study and analyze relay
connection scheme for such regulators. ( I mean we use up to five SPDT
relays to change six different tapping for auto-transformer to provide
six different turn ratios, one step down, five step up between the ac
input and output. I would like to study different combinations of relay
contact points to provide a good voltage regulation scheme)

Sola "Adjust-A-Volt"
--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
M

Myauk

Jan 1, 1970
0
Can you show me the link so that I could understand more and study the
schematic?
 
H

Homer J Simpson

Jan 1, 1970
0
In my country, I took part in design and construction of Auto
Transformer AC Voltage Regulators with automatic control of tap
changing with electromechanical relays.

Since my country is less developing country in Electrical and
Electronics product development, I would like to know if these
Electromechanical Relay Type-Automativ AC Voltage Regulators with Auto
Transformers are obselete or not.

AFAIK they are still used for electrical distribution systems.
 
E

Eeyore

Jan 1, 1970
0
Homer said:
AFAIK they are still used for electrical distribution systems.

Don't you also get motor driven variacs ?

Graham
 
R

Ross Herbert

Jan 1, 1970
0
In my country, I took part in design and construction of Auto
Transformer AC Voltage Regulators with automatic control of tap
changing with electromechanical relays.

Since my country is less developing country in Electrical and
Electronics product development, I would like to know if these
Electromechanical Relay Type-Automativ AC Voltage Regulators with Auto
Transformers are obselete or not.

Are they still required for certain applications?

If it is not useful anymore, I would study
solid-state-relay-auto-transformer type regulators, and PWM control
type, Servo motor control type AC regulator designs!

More over I would like to know how to study and analyze relay
connection scheme for such regulators. ( I mean we use up to five SPDT
relays to change six different tapping for auto-transformer to provide
six different turn ratios, one step down, five step up between the ac
input and output. I would like to study different combinations of relay
contact points to provide a good voltage regulation scheme)

The relay system you describe would appear to me capable of only
producing step-incremental voltage changes, - not what I would term a
"good voltage regulation scheme".

High power systems which I saw used around the 1970's, employed motor
driven variacs which produced a much smoother response than relay
switched schemes.
 
H

Homer J Simpson

Jan 1, 1970
0
Don't you also get motor driven variacs ?

Not for mains electrical systems. N. America seems to use a lot more smaller
pole transformers from 11 Kv. I've lived where step selected transformers
were in use - you can see the lights change brightness as the transformer
steps up or down.
 
B

Borat

Jan 1, 1970
0
The relay system you describe would appear to me capable of only
producing step-incremental voltage changes, - not what I would term a
"good voltage regulation scheme".

High power systems which I saw used around the 1970's, employed motor
driven variacs which produced a much smoother response than relay
switched schemes.

20+ yrs ago they used a motor driven system in the front end of
telecommunications rectifiers (mains AC --> 48Vdc) for regulation. Perhaps
someone remembers more about them than me?
 
R

Ross Herbert

Jan 1, 1970
0
20+ yrs ago they used a motor driven system in the front end of
telecommunications rectifiers (mains AC --> 48Vdc) for regulation. Perhaps
someone remembers more about them than me?

That's exactly the units I was referring to (at Pier Exchange in
Perth) but it was a lot earlier than the 80's. Several 48Vdc/1000A
rectifiers for battery charging.
 
H

Homer J Simpson

Jan 1, 1970
0
One good example of such a system is the GE Inductrol, which we used
with great success 35 years ago, and is still available.

I've seen my share of CVTs, however I only once ever worked on a system with
a magnetic amplifier and I don't know anyone else who has.
 
J

John Perry

Jan 1, 1970
0
Homer said:
I've seen my share of CVTs, however I only once ever worked on a system with
a magnetic amplifier and I don't know anyone else who has.

This is not a magnetic amplifier. This is a variable transformer
similar to what was described in my attribution, which you deleted.

The variable transformer adds a controllable small AC voltage to the
line voltage, with consequent smooth sine wave output.

Magnetic amplifier operation is very similar in operation to an SCR
power controller. In an SCR controller, the control signal causes the
semiconductor to be an open circuit until conditions cause it to switch
to a low resistance, with consequent waveform chopping. In a magnetic
amplifier, the control signal causes the inductor to be a high reactance
until conditions cause the core to saturate, switching to a low
reactance, with consequent waveform chopping.

jp
 
H

Homer J Simpson

Jan 1, 1970
0
This is not a magnetic amplifier. This is a variable transformer
similar to what was described in my attribution, which you deleted.

It was just an observation.
The variable transformer adds a controllable small AC voltage to the
line voltage, with consequent smooth sine wave output.

But isn't this basically a CVT?
 
E

Eeyore

Jan 1, 1970
0
Homer said:
I've seen my share of CVTs, however I only once ever worked on a system with
a magnetic amplifier and I don't know anyone else who has.

I don't know if it counts as a 'magnetic amplifier' but ~ 32 yrs ago I saw a
theatre light dimmer pack that used a DC control current in one winding of a
saturable reactor that controlled the AC load.

Quite neat really and no triac style EMI !

Graham
 
H

Homer J Simpson

Jan 1, 1970
0
I don't know if it counts as a 'magnetic amplifier' but ~ 32 yrs ago I saw
a
theatre light dimmer pack that used a DC control current in one winding of
a
saturable reactor that controlled the AC load.

Yep, same thing.
 
M

Myauk

Jan 1, 1970
0
What is CVT?
From the discussions, I understand that relay type tap-changing scheme
for voltage regulation is no longer useful in General Electrical
Applications except in some light dimming schemes, battery charging and
Generator Sets, am I right?

Has a magnetic amplifier been still being used until now? From the
point of view of power quality, I think it is a better solution
providing a good regulator with less spikes and surges, am I right?

Can anybody show me the link to the general circuit design for servo
motor controls for such moter driven voltage regulators.:- I have one
schematic by some China Company but I still need more schematics so
that I could compare the design to understand more about it!

Please explain a little bit about them for the newcomer like me, who
actually is just a few years old in Electronics Design Field. :)


Regards
 
H

Homer J Simpson

Jan 1, 1970
0
Has a magnetic amplifier been still being used until now? From the
point of view of power quality, I think it is a better solution
providing a good regulator with less spikes and surges, am I right?

Last one I saw was in a sewage pumping station about 40 years ago. It was
controlling a DC pump motor and we connected it to a depth gauge to control
the depth in the holding tanks.
 
J

Jamie

Jan 1, 1970
0
Eeyore said:
Homer J Simpson wrote:




I don't know if it counts as a 'magnetic amplifier' but ~ 32 yrs ago I saw a
theatre light dimmer pack that used a DC control current in one winding of a
saturable reactor that controlled the AC load.

Quite neat really and no triac style EMI !

Graham
yes, it has a 3 pole core. very common in the old days for variable
control from a low power source of DC>
 
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