Capacitor start single phase motor

  • Thread starter notsosmart
  • Start date
  • #1

Main Question or Discussion Point

hi

I have been given the task to sort out a broken barrier at the entrance to my work. It is a simple enough system, push button to go up/down and a stop button. Within the barrier mechanism is 2 pistons (one for up, one for down) which are controlled by a hydraulic pump. The pump has a single phase capacitor start motor. This is bidirectional to control either of the pistons.

My problem; the direction of the motor is controlled by an electronic circuit board mounted within the barrier mechanism. This is continually getting wet and failing no matter how much we try to protect it. I now want to build my own system with either a plc unit, or simply relay system, away from the barrier itself to protect from the elements. I am unsure the best way to do this for the reversal of the motor direction. The motor core colours from the built in flex are brown, blue, black, earth, which i assume is switch wire, neutral, switch wire, earth?? Do i need 2 capacitors, one for each switch wire? any help greatly appreciated.
 

Answers and Replies

  • #2
4,662
5
In a standard FHP capacitor-start motor, there are two pairs of leads, the motor-run leads and the motor-start leads. All you need to do to reverse the direction of the motor is reverse the polarity of one pair. You cannot reverse the direction of a running single phase induction motor (most, anyway).

Bob S
 
  • #3
dlgoff
Science Advisor
Gold Member
3,814
1,742
The pump has a single phase capacitor start motor. This is bidirectional to control either of the pistons.
Are you sure the control unit is not just operating a valve to switch the fluid between the pistons?
 
  • #4
thanks.

the motor is continually changing direction for the up or down movement of the barrier. After Don asking, i double checked this. The motor has a pre-wired flex to it with 3 cores and earth. As it is single phase, i presumed it must be two switch wires and a neutral? is my logic wrong here?? please advise, thanks.
 
  • #5
page 2 of this link shows the hydraulic unit that im on about. And the electronic board within enclosure that has been so problematic. http://www.ecssecurity.co.uk/pdf/info/FAAC%20620%20TRAFFIC%20BARRIER.pdf [Broken]
 
Last edited by a moderator:
  • #6
4,662
5
See page 3 of this:

http://igor.chudov.com/manuals/ElectricMotors.pdf

Reverse the connections of wires #5 and #8 in illustration on 3rd page to reverse direction of starting coil. You will need a double pole double throw (DPDT) switch to do this. The motor direction could be reversing automatically due to either physical limit switches or excessive torque (hydraulic pump pressure) switches.

Bob S
 
  • #7
thanks to all. problem now solved.
Using a small bank of relays (plc unit was prob not worth paying for) we have now set a system that works ok. The pump needed to be switched over by manually reversing the polarity like bob explained. This was achieved by the way we wired it.

cheers guys, appreciated

martin
 

Related Threads on Capacitor start single phase motor

  • Last Post
Replies
4
Views
8K
Replies
5
Views
56K
  • Last Post
Replies
3
Views
979
  • Last Post
Replies
7
Views
9K
  • Last Post
Replies
1
Views
3K
  • Last Post
Replies
9
Views
1K
  • Last Post
Replies
5
Views
4K
Replies
1
Views
701
  • Last Post
Replies
1
Views
3K
Replies
1
Views
878
Top