Overhead hoist

LesJones

Joined Jan 8, 2017
4,511
Hi Kevin, Can I confirm a few things.
1 You say you have changed a contactor. (But you have not said which one.) Am I right in assuming that it is the one in the box next to the transformer ?
2 That it is the one that is actuated by the ON button :
3 That the two westinghouse contactors are actuated by UP and Down buttons . (One by each button.)
4 Assuming my above assumptions are correct when the new contactor is fitted you say the crane does not work.
When the ON button is pressed is the new contactor actuated ?

Is the transformer just supplying a low voltage for the control circuit ? (The contactor coils.)
Do you know the voltage rating of the coils on the contactors ?

Les.
 

Thread Starter

Kevin79

Joined Aug 16, 2021
43
Hi Kevin, Can I confirm a few things.
1 You say you have changed a contactor. (But you have not said which one.) Am I right in assuming that it is the one in the box next to the transformer ?
2 That it is the one that is actuated by the ON button :
3 That the two westinghouse contactors are actuated by UP and Down buttons . (One by each button.)
4 Assuming my above assumptions are correct when the new contactor is fitted you say the crane does not work.
When the ON button is pressed is the new contactor actuated ?

Is the transformer just supplying a low voltage for the control circuit ? (The contactor coils.)
Do you know the voltage rating of the coils on the contactors ?

Les.
I replace th AB box by the transformer. It is the on. With the old AB it works holding on. the crane moves on the tracks. One button is traveling back and one will travel forward.
New AB contactor installed it does turn on and cuts off when releasing the button just like the old one. The difference is the new contactor with the on held and coil activated the crane will not move at all.
I reinstalled old one and it moves with the on button held. If it was in the pendent it would in theory work same on both units right?
 

LesJones

Joined Jan 8, 2017
4,511
There is a fault on the new contactor related to the three main contacts and the path though the overload trips. The information sheet in the picture in post #21 shows these paths. The three phase power enters on terminals L1, L2 and L3. The path first goes through the three main contacts then through the heaters for the thermal trips. The three phase output is on terminals T1, T2 and T3. When the coil is activated there should be a path through from the L terminals to the corresponding T terminals. This path is not being made on the new contactor. When the current through the thermal trip heaters is too high they heat bimetal strips which bend when hot. When any one of the three bimetal stips bend enough they trip a mechanical latch which causes a set of NC contacts to open. (The latch can be reset by pressing the white button.) These NC contacts are wired in series with the contactor coil to prevent the contactor from being activated. I think the two screw terminals with the orange wires connected to them are the coil connections. I think the connections marked 2 and 3 are the maintainer contacts. (NO contacts.)
Looking at the picture in post #22 it looks like the thermal overload contacts have been bypassed. (Two wires are connected to the same terminal on the NC contact set.)
When your original fault is fixed wee can see about finding the fault with the new contactor.

Les.
 
Last edited:

zophas

Joined Jul 16, 2021
165
@Kevin79, have you checked the OFF button in the pendant? Is it functioning properly? How are you doing with a schematic for the crane wiring? It would be good to have one in case of future problems too. I agree with @LesJones , let's fix your original problem and then tackle the new contactor problem.
 

LesJones

Joined Jan 8, 2017
4,511
Can you measure the voltage between the terminals circled in yellow with the ON button held pressed. I think these are the coil terminals. The test is for us to find out if the coil is powered from a low voltage, phase to phase voltage or phase to neutral voltage. What is the phase to phase voltage in your country ? (I have been assuming it is about 415 volts.)
Can you post a picture looking directly into the box so we can at least try to follow the wires.
I agree with zophas. With the crane fully isolated from power measure the resistance between the terminals on the stop button in the control pendant with the stop button NOT pressed.

190821.jpg

Les
 

Thread Starter

Kevin79

Joined Aug 16, 2021
43
Can you measure the voltage between the terminals circled in yellow with the ON button held pressed. I think these are the coil terminals. The test is for us to find out if the coil is powered from a low voltage, phase to phase voltage or phase to neutral voltage. What is the phase to phase voltage in your country ? (I have been assuming it is about 415 volts.)
Can you post a picture looking directly into the box so we can at least try to follow the wires.
I agree with zophas. With the crane fully isolated from power measure the resistance between the terminals on the stop button in the control pendant with the stop button NOT pressed.

View attachment 245987

Les
I will measure that in 30 min. Les you are awesome
 

zophas

Joined Jul 16, 2021
165
That's weird. Where I come from crane companies seldom fail to display their name in big letters all over their cranes. It's good advertising space.
 

Thread Starter

Kevin79

Joined Aug 16, 2021
43
As a follow up to my post #51, If this is a fairly crucial piece of equipment, considering its apparent age, it is most likely going to benefit from a update/retrofit. Complete with a ladder drawing.
I agree. Im trying to get all my parts listed and make sure everything is compatible
 
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