[TowerTalk] Looking for UST Control Box

[Roger (K8RI) on TT]

When used properly, the limit switches are an additional 2 sets of 
contacts.  Any additional sets of contacts do serve as additional 
safety. Mine are Microswitches which are widely used in industry.  If 
you are not satisfied with the reliability, purchase SPDT Microswitches 
and the enclosures for exterior use. They are very reliable. The 
companies I worked for over the years all used Microswitch limit 
switches as do most of my machine tools.

There are no relays in my control box, nor is there a key switch. The 
power comes from an extension cord which is only hooked up when raising, 
or lowering the tower.  Emergency shutoff is simply pulling the plug.

I thought about copying the original setup and decided on simple. 
Operation is a simple  DPDT, spring return, center off 10A 120 VAC bat 
handle, toggle switch.

73

Roger  (K8RI)


On 7/23/2016 Saturday 7:41 PM, Richard (Rick) Karlquist wrote:
>
>
> On 7/23/2016 3:25 PM, Roger (K8RI) on TT wrote:
>>
>> I'd definitely want limit switches.  They are good insurance.
>>
>> 73
>>
>> Roger (K8RI)
>>
>
> Actually, limit switches are NOT good insurance.  They
> don't protect against the contactor sticking.  The
> contactor used is the same kind that air conditioners
> use, and air conditioner contactors are famous for
> sticking.  Read about that on the internet.
>
> What you need for insurance is a local (on the box)
> power switch that cuts the power to the MOTOR.  The
> power switch built into the control box only cuts
> the power to the coil of a relay that in turn cuts
> the power off to the COIL of the contactor.  I had
> to add a real power cutoff switch to the box.
>
> I have had a contactor stick twice.  Fortunately, I
> was standing next to the control box monitoring
> when it happened and was able to pull the big switch.
>
> Rick N6RK


-- 

73

Roger (K8RI)


---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus