AB SMC Flex soft starter

srv

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Aug 2010
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Hi,

I have one SMC FLEX soft starter.When I connected to Power soft starter showing full output voltage even with out control Off.I am using terminal 16 & 17 for control (on / Off).Soft starter is showing "stopped".I checked with out load (Motor is not connected).Is it the reason for the out put voltage even starter is stopped.Anybody please advice me.
 
Why are you using Terminal 16? What do you have Optional Terminal 16 programmed to be or do? If you want to control the drive without the need to program terminal 16 to be some function, then use the standard terminal 17 (Start) and terminal 18 (Stop), as shown in the manual. With no wiring connected to the STOP input terminal 18 (Open Stop Switch), the drive will think it is being given a STOP command.

Allen Bradley SMC Drive Terminals.jpg
 
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I want to give a start command from a PLC digital output.(Through relay contact).So there will be no srart and stop push button.In the manual it is showing some connection for the same use.It is shown connection from relay to terminal 16 and direct connection to terminal 17 and 18 not connected.When we connect to 16 Starter showing "starting" and tripping with "no Load" ( Because I did not connect the motor to starter).But when I checked the starter terminal with out start command enabled,it showing 400V.If Starter is "stopped".Output voltage should be Zero right?.So I am scared to connect the motor terminals to the started.It is brand new starter and I have two starters showing same proble.
 
In the manual, it is showing some connection for the same use. It is shown connection from relay to terminal 16, and direct connection to terminal 17 and 18 not connected.
That wiring method only works if you "program" Terminal 16 for one of the optional (can use it but it is not mandatory) Option #1 functions.

See the SMC-Flex User Manual, Page 4-3, Figure 4.2. Look under menus "Parameter, Set Up, Basic, Option 1 and Option 2". Now go to Page 4-14, "Basic Set Up". Look down the parameter list to "Option 1 Input" (Parameter number 132).

Option 1 (Terminal 16) can be set for the following functions: "Disable, Coast, Stop Option, Fault, Fault NC, or Network". The default factory setting for Option 1 is "Stop Option". With that setting, Terminal 16 can be used to STOP the SMC, but not START it. See also Appendix B "Parameter Information", Page B-13, Table B.1 for the Option 1 Parameter # 132 details.

Unless YOU set Option 1 to one of the above correct programmed functions, your wiring will not work correctly to allow Terminal 16 to be used to start up the Soft Starter.

Why do this the hard way? Why not use a standard Stop-Start Input (it can be ONE input device) wired to Terminals 17 and 18 (as shown on Page 3-13 "Standard Controller Wiring", Figure 3.11)? Then you would NOT have to set paramaters for Option 1 and Option 2.

SMC-Flex Standard Wiring Diagram.jpg
 
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Thanks Lancie.Is it normal ,getting voltage on output terminals when terminal 16 is not connected.
 
I don't know if it is normal to measure a voltage on the SMC output terminals (from phase to phase) with no load connected. Because the outputs are most likely controlled by switching power transitors, it could be normal to measure a voltage under no-load conditions.
 
I don't know if this applies to the SMC or not, but it isn't uncommon for solid state relays to have some voltage leakage when they are floating - unconnected to a load. If the motor is hooked up you probably won't see it spin because there is essentially no current getting through. I suggest you talk to your distributor.
 
What size are these SMC Flex's that you are using, on the larger ones there are 2 sets of outputs, for use on inside Delta wired motors, one set of terminals is wired straight through and the other set are controlled, the straight through terminals are at the same height as the input terminals (they are the same bus bars), the controlled outputs are closer to the back and sometimes come supplied with a cover over them.

Alan

I think you will find that they are SCR's not transistors in the SMC's.
 
I think you will find that they are SCR's not transistors in the SMC's.
Then the SCR's definitely have a small leakage current in the off state, that could cause a high-resistance voltmeter to read a voltage. If the motor will run without an SCR Gate pulse signal (Start not ON), then the SCR Ouptuts are probably shorted out and will have to be replaced. On the other hand, if the SCR Gate signal is removed, and the SCR Outputs go off, then there is a problem with the Start circuit or the SCR gate control device.
 
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should there be still connection in pin 16 to phase (hot wire)? eventhough i am using pin 17 and 18 to start and stop the soft starter?
 
All SCRs leak a small amount and it can be read by most modern digital VMs as the full line voltage even if the starter is in the Off state. In addition, SCRs used in Soft Starters also have an RC Snubber circuit in parallel with the SCRs, and that too has leakage through it that can be read by a sensitive enough DMM. But the amount of current will be less than 6mA if you use a current meter (sensitive enough to read that). If the current is greater than 6mA then you MIGHT have a problem. If you suspect that, perform the Shorted SCR test procedure described on page 9-7 of the manual.
 
MOTOR NOT CONNECTED
The internal switch is an SCR without a motor or load connected to the output you will read line voltage with volt meter. It's called leakage current all solid state devices leak without a load the full line VT age will be read on the output
Connect the motor and recheck I would bet the output voltage will read 0 or normal

Also I would check the manual I don't think soft starts like to be powered without a load connected you could damaging it. I think it has to do with Co mutating the SCR off it needs current flow to do that
 
No motor connected will not damage the soft starter, but it will not do anything, there is no point in doing so even for "testing" because there will be nohing to test. If you need to test functionality, use a small 3 phase motor, but understand that it will only run for about 3 seconds before tripping on under load; the soft starter will need to see at least 20-30% of rated load to stay on.
 
you can believer that if you want some can run without a load and some can not it all depends on how they are made. I have seen both but why take the chance if you get it wrong you blow the soft start. Without some kind of a load the leakage of the solid state devise will read as full voltage on a voltmeter. so do your testing with a motor connected
I have seen the leakage current cause a lot of problems in the past. I just had on a few weeks ago a prox switch leakage would not turn off an input I had to put lamp on the input to load it down.
 
Hi all,
I am having SMC Flex for pump application. I am getting HALL ID #38 fault. As per manual it says to change the power module. I checked power module and found ok. (T1-L1, T2-L2, T3-L3 R>1M.Ohm. What should i do. The same module was working fine earlier.
 

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