S
swalchemist
Guest
Let me be a bit clearer here, in this case "pump" refers to only impeller driven units. All internal and some smaller external pumps in our hobby are built in this manner. AC is alternating current DC is direct current. You can shut off and turn on a DC driven impeller or propeller and it will start the same direction every time. Where an AC driven impeller will start up either forward or in reverse when power is applied that's why they have to have mechanical braking devices to stop the impeller then restart it. This insures the prop spins in the right direction only. Even the Tunze Nano Stream 6025 and 6045 have the same problems as they are AC driven pumps. It is possible to create a circuit that produces a false direct current which can insure the pumps start in the same direction or never completely powers down in the first place.
b bauer
Member
ac pumps DO NOT go backwards because of AC current if that where the case then your furnace blower mtr would go backwards your fridge compressor mtr also the HOB filter pumps and there is no impeller driven mtr the impeller is on the output shaft your electrical theory is wrong.The mtr might spin backwards not because of an AC field.the motor that is on an ph is the same as a furnace blower mtr just a bigger version
aloysiusii
Member
Like they said they look sweet as "F" in the tank I would like to get one or two does any one have any for sale??? let me know!!!!
S
swalchemist
Guest
AC motors generally come in two types: single phase and three phase.
Single-phase AC synchronous motors
"Small single-phase AC motors can also be designed with magnetized rotors (or several variations on that idea). The rotors in these motors do not require any induced current so they do not slip backward against the mains frequency. Instead, they rotate synchronously with the mains frequency. Because of their highly accurate speed, such motors are usually used to power mechanical clocks, audio turntables, and tape drives; formerly they were also much used in accurate timing instruments such as strip-chart recorders or telescope drive mechanisms. The shaded-pole synchronous motor is one version.
Because inertia makes it difficult to instantly accelerate the rotor from stopped to synchronous speed, these motors normally require some sort of special feature to get started. Various designs use a small induction motor (which may share the same field coils and rotor as the synchronous motor) or a very light rotor with a one-way mechanism (to ensure that the rotor starts in the "forward" direction)."
http://www.international-electrical-...motors-ac.html
Single-phase AC synchronous motors
"Small single-phase AC motors can also be designed with magnetized rotors (or several variations on that idea). The rotors in these motors do not require any induced current so they do not slip backward against the mains frequency. Instead, they rotate synchronously with the mains frequency. Because of their highly accurate speed, such motors are usually used to power mechanical clocks, audio turntables, and tape drives; formerly they were also much used in accurate timing instruments such as strip-chart recorders or telescope drive mechanisms. The shaded-pole synchronous motor is one version.
Because inertia makes it difficult to instantly accelerate the rotor from stopped to synchronous speed, these motors normally require some sort of special feature to get started. Various designs use a small induction motor (which may share the same field coils and rotor as the synchronous motor) or a very light rotor with a one-way mechanism (to ensure that the rotor starts in the "forward" direction)."
http://www.international-electrical-...motors-ac.html
