- Joined
- Feb 2, 2013
- Messages
- 4,097
i recently had some time to tinker in the garage.
i was able to construct a 10HP Star Delta motor starter for use on 6 wire and 9 wire motors.
drawings shown are for 6 wire motors only!
for the uninitiated, a star delta motor starter uses contactors to switch between star and delta motor wiring.
star wound motors draw 1/3 the start up current vs the delta wound motor for the same Hp rating.
the disadvantage to a star wound motor, is that it has 1/3 the torque of a delta wound motor.
the star delta control system can be considered a hybrid of sorts.
the motor starts in lower amp draw conditions of the wye(star) winding connection for starting, and switches to delta winding connection for higher efficiency.
at around 80% of the motor's rated speed the wye(star) winding , becomes less efficient to power a motor than the delta configuration of the windings.
at near peak of the wye(star) potential (or shortly thereafter) , the solid state timer will switch contactors responsible from star to delta operation.
star delta switching can be done manually, or by means of a solid state timer relay.
i made both iterations before deciding the later as the design i will stick with.
this is not the only way to accomplish the end result, this is how i did it....
first the sketch...
then construction...
i had 90% of the components lying around the shop, i ordered a couple items from amazing and epay.
i wired up the control system first, then wired the line connections.
i used a 25 amp main contactor an overload relay capable of 18 amps , 2, 20 amp contactors for the star and delta, 2 22mm momentary switches (1NC, 1NO), 1 22mm maintained contact switch (NC), a solid state timer, some DIN rail, wire ferrules, spade and fork connectors, control wiring and,SOOW cable
i had to test the system out so i made a short video explaining the control system and giving a op demo without a motor in series
if you got nothing better to do for the next 7 minutes, have a look....
i made a drawing of the control system as in operation, for the interested.
(note: transformer supply and/or MCCB use recommended, as is the overload relay and interlocking contactor operation, for simplicity MCCB and Transformer not shown in drawings)
after making the video,
i went on a scavenger hunt around the garage and found a small .1Kw motor to run with the star delta system.
the problem is that i don't have 3 phase readily available .
after rummaging around i found my stash of small oil filled run capacitors- i found a 7.5 Uf capacitor.
capacitance values for running 3 phase motors on single phase is about 70Uf per 1Kw or about 53Uf pr Hp
the .1 Kw motor would require 7Uf capacitance , the 7.5 Uf capacitor i have will work fine although it has slightly higher capacity.
i was able to supply single phase 240v and wire in the run capacitor and run the small motor on single phase in both delta and star.
here's the video....
i also made a full circuit drawing of the single phase operation for the interested. (MCCB and Transformer omitted)
i'll be starting larger motors soon!
stay tuned!!!
i was able to construct a 10HP Star Delta motor starter for use on 6 wire and 9 wire motors.
drawings shown are for 6 wire motors only!
for the uninitiated, a star delta motor starter uses contactors to switch between star and delta motor wiring.
star wound motors draw 1/3 the start up current vs the delta wound motor for the same Hp rating.
the disadvantage to a star wound motor, is that it has 1/3 the torque of a delta wound motor.
the star delta control system can be considered a hybrid of sorts.
the motor starts in lower amp draw conditions of the wye(star) winding connection for starting, and switches to delta winding connection for higher efficiency.
at around 80% of the motor's rated speed the wye(star) winding , becomes less efficient to power a motor than the delta configuration of the windings.
at near peak of the wye(star) potential (or shortly thereafter) , the solid state timer will switch contactors responsible from star to delta operation.
star delta switching can be done manually, or by means of a solid state timer relay.
i made both iterations before deciding the later as the design i will stick with.
this is not the only way to accomplish the end result, this is how i did it....
first the sketch...
then construction...
i had 90% of the components lying around the shop, i ordered a couple items from amazing and epay.
i wired up the control system first, then wired the line connections.
i used a 25 amp main contactor an overload relay capable of 18 amps , 2, 20 amp contactors for the star and delta, 2 22mm momentary switches (1NC, 1NO), 1 22mm maintained contact switch (NC), a solid state timer, some DIN rail, wire ferrules, spade and fork connectors, control wiring and,SOOW cable
i had to test the system out so i made a short video explaining the control system and giving a op demo without a motor in series
if you got nothing better to do for the next 7 minutes, have a look....
i made a drawing of the control system as in operation, for the interested.
(note: transformer supply and/or MCCB use recommended, as is the overload relay and interlocking contactor operation, for simplicity MCCB and Transformer not shown in drawings)
after making the video,
i went on a scavenger hunt around the garage and found a small .1Kw motor to run with the star delta system.
the problem is that i don't have 3 phase readily available .
after rummaging around i found my stash of small oil filled run capacitors- i found a 7.5 Uf capacitor.
capacitance values for running 3 phase motors on single phase is about 70Uf per 1Kw or about 53Uf pr Hp
the .1 Kw motor would require 7Uf capacitance , the 7.5 Uf capacitor i have will work fine although it has slightly higher capacity.
i was able to supply single phase 240v and wire in the run capacitor and run the small motor on single phase in both delta and star.
here's the video....
i also made a full circuit drawing of the single phase operation for the interested. (MCCB and Transformer omitted)
i'll be starting larger motors soon!
stay tuned!!!
Last edited:
