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    Ultra-Cut and Auto-Cut Demand Signals

    作者: 本站 來源: 本站 時間:2016年04月27日
      Demand Signals – Cutting & Pilot
      Analog voltages are sent from the CCM to the power supply WK-5602 board and  from there to the inverter module(s) and pilot regulator (chopper) to set the expected output currents. These are referred to as Demand signals.  
      Pilot Demand at the CCM output is available on TP14 (TP1 common) of the CCM I/O PCB and Cut Demand at TP13.  These demands are set to zero before Start signal is applied. Then, at beginning of preflow, are set to their initial values.

      Cut Demand – CCM
      CCM can receive Cut Demand signals from a number of paths.  If the system is an Autocut with GCM 1000, cut demand is set from current control pot on GCM front panel.  
      With GCM 2000 or 2010 cut demand comes from the Gas Control over the CANBus fiber optic link. If GCM3000 (automatic gas control) is used, cut demand is from HMI over fiber optic link.

      GCM1000 Current Control
      When GCM 1000 is used, a jumper in the gas control is connected across  gas control connector J56-8 & 9, which, through J55-8 & 9, power supply rear panel GCM connector,  makes signal “Basic ID”, at CCM I/O PCB J7-2 (J7-1 common), true (low) telling CCM  to look for Cut Demand signal from GCM1000’s current control pot.

      Remote Analog Current Control
      Another option that can be used with any system is a remote isolated analog 0-10V signal applied to CCM I/O PCB’s TB1-10(+) & 9(-) or rear panel CNC  connector J15-10(-) & 11(+).  To use the remote analog voltage, set CCM CPU board’s DIP SW8-2 ON and set SW 11 on CCM I/O PCB to position “A” (down).  This points out a possible fault condition, if either but not both of the switches is set for remote analog cut demand, cut demand will effectively be zero. Unit may pilot but either will not transfer or may transfer then immediately go out.  Same is true if both are set for remote analog current control but no analog voltage is connected.

      Demand Scaling
      Eagle systems power supplies are designed for maximum outputs of 100, 150, 200 & 300A.  All supplies have a minimum current of 10A. The Cut Demand signal is linearly scaled for 0 to 10V = 0 to maximum amps.  For example, on a 100A supply, Cut Demand can range from 1V (10A) to 10V (100A).  On a 300A power supply 10V = 300A and 1V = 30A. 10A demand is 0.33V.   
      The operator sets the desired cutting current. Prior to receiving Start signal, Cut Demand at TP13 is set to zero.  At Start and during preflow the CCM module sets the Cut Demand  voltage (TP13) at an initial level based on the desired cutting current setting. See table below for initial voltage levels.  At arc transfer, CCM ramps the Cut Demand up to the cutting current level set by the operator over 100 ms. (default).  Cut Demand can be measured on the CCM I/O PCB TP13 (TP1 common) while cutting.   Initial level can be measured at TP13 by method described for above for Pilot Demand (disable RAS, Cut Demand present for preflow plus 15 seconds).

      Some of these values are preliminary and may change a little with later CCM revisions.
           Initial Cut Demand  -- Chopper Pilot Systems
      Cut Current    100A  SYS    150A  SYS    200A  SYS    300A   SYS
      0-10    1.5    1.0    0.8    0.5
      11-25    1.6    1.1    0.8    0.5
      26-35    1.8    1.2    0.9    0.6
      36-55    2.1    1.4    1.1    0.7
      56-75    2.3    1.5    1.2    0.8
      76-105    2.6    1.7    1.3    0.9
      106-135    -    1.9    1.4    0.9
      136-155    -    2.0    1.5    1.0
      156-210    -    -    1.8    1.2
      211-300    -    -    -    1.3
      Some early power supplies have pilot resistor(s) instead of chopper regulators. For those units Initial Cut Demand will be slightly higher.

      Cut Demand- WK-5602 -- Chopper Pilot Units Only
      Do not make measurements on WK-5602 board with HF firing.  Noise may be introduced than can cause catastrophic unit failure.  Instead use following method for Measuring Demand Signals with RAS Disabled.
      Measuring Demand Signals with RAS Disabled
      To measure demand signals without introducing HF noise disconnect the RAS (Remote Arc Starter) control cable at the RAS end, J58, so the pilot doesn’t start.  At the end of preflow CCM will attempt to ignite pilot for 15 sec.  (Because pilot won’t ignite, status code 1-2 will flash on power supply front panel). The CCM will apply the Pilot Demand and Cut Demand  for preflow time (default 2 sec but can be increased up to 8 sec if more time is needed) plus 15 sec. ignition time giving enough time to measure with voltmeter.  Pilot starting level is background.

      Cut Demand leaves CCM I/O PCB from J35-2 (26 ckt ribbon cable) and goes to CN10 (other end of ribbon cable) on WK-5602 PCB.  Cut demand is filtered, scaled to 80% of input (100, 200, & 300A) or 60% (150A) and renamed as I_REF.   I_REF is sent to the inverter module(s) on CN6 (16 ckt ribbon cable).  
      WK-5602 board has a few test points labeled TP # and a number of vias labeled with letters that can be used as measurement points after pushing through the conformal coating.  For most measurements TP0 is board ground or common.

      Cut demand entering WK-5602 board can be measured at via “A” (TP0 common) next to CN10.  Cut Demand (I_REF) exits the board at CN6-2. Can be measured at via “G” near IC1.
      The way to troubleshoot this is measure the incoming Initial Cut Demand level at CCM TP13 then measure I_REF at via “G” on WK-5602. Value should be 80% (60% if unit is 150A) of the Initial Cut Demand.  If it does not, measure Initial Cut Demand where it enters WK-5602 at via “A”.  If it is not correct, not the same as at TP13 on CCM, then ribbon cable or connections are defective.  If Initial Cut Demand at via “A” is correct  WK-5602 board may be defective.  Measure   WK-5602 board bias supplies. From TP0,  gnd, measure TP1 for  +5 VDC; TP2 for +15 VDC; TP3 for -15 VDC. If these are correct WK-5602 board is defective. If one or more bias supplies are not correct go to section __________ to troubleshoot bias supplies.

      Pilot Demand - CCM
      The Eagle systems pilot circuits are designed for min of 15A and max up to 50A.  The Pilot Demand signal is scaled for 0-10V = 0-50A.  During Piloting the pilot current is pulsed between two levels, a peak level and a background level.  Pilot is ignited with pilot demand at background to reduce overshoot.  Background for cutting at 75A and below is 15A (3 V. Pilot Demand), cutting above 75A background is 18A (3.6V).

      As soon as pilot current is sensed by Pilot On becoming true (CCM I/O PCB J36-4 34 ckt ribbon cable, true = low), Pilot Demand is then immediately (1-2 ms.) brought up to peak for a first pulse of 50 ms. duration.  Demand then drops to background for 30 ms. Subsequent pulses are about 4 ms. duration with 30 ms. at background between pulses.      
      Cut Current         Pilot Peak Current
      0-10         15
      11-25         17
      26-35         20
      36-55         24
      56-75         27
      76-105         33
      106-135         36
      136-155         40
      156-210             45  *
      211-300             50  *
      * These are preliminary, may be reduced.

      There are two settings for pilot time, the factory default setting allows up to 85 ms.  The other setting gives up to 3 seconds and is used for general purpose, not high tolerance, cutting where you are doing running edge starts. Parts life will be reduced if longer pilot times are used.  If pilot times out without an arc transfer sets error code #1-3.
      Pilot Current Demand can be measured at TP14 (TP0 common) on CCM I/O PCB.  Due to the pulsing and short duration it is best measured with an oscilloscope.  
      Pilot demand –WK-5602 -- Chopper Pilot Units Only
      Do not make measurements on WK-5602 board with HF firing.  Noise may be introduced than can cause catastrophic unit failure.  Instead use method above Measuring Demand Signals with RAS Disabled where RAS is disabled and Pilot Current Demand is present at initial level, 3V., for 15+ seconds.  
      Pilot Demand leaves CCM on J35-4 (26 ckt ribbon cable) and goes to CN10-4 (other end of ribbon cable) on WK-5602 board.  Pilot Demand is filtered, scaled to 80% of input and renamed  I Pilot Ref. It leaves WK-5602 for the Chopper module on CN33-3. Initial level at CN33-3 will be 2.4V.  Common is CN33-4 or TP 0.  TP0 is common on this and other power supply boards.  Boards made by TDC (CCM, Gas Controls) use TP1 as common TP. 
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