single phase to 3-phase converter

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single phase to 3-phase converter

Post by longthrow on Wed Feb 08, 2012 9:38 am

ways of producing 3 phase ac from single phase:

1)a motor-generator set (m-g set) where a single phase motor drives a 3
phase generator which is bulky, expensive & complex

2)electronic inverters using power igbts or mosfets controlled by
processors which produces the "ideal" 3-phase but is very expensive and
more comlpex.

3)Static converters that use a transformer to produce 2 phases from one,
and at the required voltage, plus a capacitor to produce a third phase when
a load motor is connected. Such a converter is cheap to manufacture but has
four serious disadvantages:

a) the load must be a motor and it must be known in advance if it is star
or delta connected
b) if the load has more than one motor then the highest power motor must
always be switched on first
c) the load motor will only run at 70% of normal torque
d) there is a minimum power limit as well as a maximum so the capacitor
value must be manually switched to match the load.

4)Rotary converters add an unloaded motor-generator to the static
converter, eliminating problems a) to d). The motor-generator can be
considered as analogous to the flywheel of an internal combustion engine;
it smooths the flow of power and maintains the equal time relationship
between the three phases. Efficiency is much higher than for an inverter
solution, reaching 95% for most of the power range.


basic rotary converter:
Tesla polyphase induction motors


modified with magnetic contactors & relays:


pb=push-button switch (start=green, stop=red)
k1=k4=20-50A 220vac magnetic contactor (150% of motor FLA rating; limit under 10hp)
k2=k3=5A 220vac relay
t1=220v 0-30 sec timer relay
olr=overload relay set @ 2-3 sec; starting time depends on the motor size
c1=c2=12-16uf per motor's hp
c3=50-100uf per motor's hp
l=220v pilot lamps
m=1-10hp 220v 3-ph induction motor

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Re: single phase to 3-phase converter

Post by Digitap on Mon Feb 13, 2012 12:36 pm


wow galing. +1 po kayo

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Re: single phase to 3-phase converter

Post by longthrow on Tue Feb 14, 2012 3:28 pm

longthrow wrote:
t1=220v 0-30 sec timer relay
olr=overload relay set @ 2-3 sec; starting time depends on the motor size

error sa typing! scratch correction:
t1=220v 0-30 sec timer relay, set @ 2-3 sec; starting time depends on the motor size
olr=overload relay set @ motor's fla (full-load amps)

@mayalin: thanks!

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Re: single phase to 3-phase converter

Post by volter on Thu Jun 07, 2012 6:09 pm


plus one point sayo sir

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Re: single phase to 3-phase converter

Post by jojogreg on Wed Oct 03, 2012 3:14 pm

+1 syo din sir..marmi ako matutunan dito..tambay lang muna.

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Re: single phase to 3-phase converter

Post by DJFEL on Wed Jun 19, 2013 10:34 pm

longthrow wrote:ways of producing 3 phase ac from single phase:

1)a motor-generator set (m-g set) where a single phase motor drives a 3
phase generator which is bulky, expensive & complex

2)electronic inverters using power igbts or mosfets controlled by
processors which produces the "ideal" 3-phase but is very expensive and
more comlpex.

3)Static converters that use a transformer to produce 2 phases from one,
and at the required voltage, plus a capacitor to produce a third phase when
a load motor is connected. Such a converter is cheap to manufacture but has
four serious disadvantages:

a) the load must be a motor and it must be known in advance if it is star
or delta connected
b) if the load has more than one motor then the highest power motor must
always be switched on first
c) the load motor will only run at 70% of normal torque
d) there is a minimum power limit as well as a maximum so the capacitor
value must be manually switched to match the load.

4)Rotary converters add an unloaded motor-generator to the static
converter, eliminating problems a) to d). The motor-generator can be
considered as analogous to the flywheel of an internal combustion engine;
it smooths the flow of power and maintains the equal time relationship
between the three phases. Efficiency is much higher than for an inverter
solution, reaching 95% for most of the power range.


basic rotary converter:
Tesla polyphase induction motors


modified with magnetic contactors & relays:


pb=push-button switch (start=green, stop=red)
k1=k4=20-50A 220vac magnetic contactor (150% of motor FLA rating; limit under 10hp)
k2=k3=5A 220vac relay
t1=220v 0-30 sec timer relay
olr=overload relay set @ 2-3 sec; starting time depends on the motor size
c1=c2=12-16uf per motor's hp
c3=50-100uf per motor's hp
l=220v pilot lamps
m=1-10hp 220v 3-ph induction motor

okis to...

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Re: single phase to 3-phase converter

Post by james on Thu Jun 20, 2013 4:28 pm

Ngayon ko lang nabasa ito. Meron pa kayang follow up?

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Re: single phase to 3-phase converter

Post by daltanics on Mon Jun 24, 2013 2:47 am

sir longthrow, pwedi ba ma  klaro ko yong control circuit mo,medyo potol,tanong kulang sir gagana ba ang electronic phase sequencer(under voltage,lower voltage  protection relay)1phase to 3 phase?thanks

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Re: single phase to 3-phase converter

Post by longthrow on Wed Jul 31, 2013 8:48 pm

sir daltanics,
meron kaba clearer pic or model ng protection relay?
meron kasi pang single phase na relay, meron din pang 3ph.
if you are using 3ph relay into single ph operation, naka protect na kaagad yan kc absent ang 2 phases (no phase voltage).

hidi yan putol sir, that is converting a single phase line into 3 phase utilizing a 3ph motor into a 3ph generator aka rotary converter.

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Re: single phase to 3-phase converter

Post by daltanics on Mon Aug 05, 2013 12:13 am


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Re: single phase to 3-phase converter

Post by daltanics on Mon Aug 05, 2013 12:24 am

ok sir longthrow,ito kadalasan genagamit sa mga control ng sub. pump dito sa riyadh.

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Re: single phase to 3-phase converter

Post by longthrow on Mon Aug 05, 2013 12:24 pm

phase monitor, over & under voltage protection relay pala yan sir.
'yan hawak nyo ay pang 3ph na variant, as indicated sa label (3ph/380v) , pero meron din naman pang 1ph na ganyang relay sir.

eto specs nyan sir:
http://www.jyhkuen.com.tw/monitor/ejvm.pdf

similar relay pang 1ph:
http://store.acradiosupplyinc.com/nter67-11a10-120relay-vltgmonitor120vac.aspx

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Re: single phase to 3-phase converter

Post by Xyphro on Wed May 28, 2014 12:01 am

aus ha thnx sa information

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Re: single phase to 3-phase converter

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