NT Engineers DigiCut PLASMA THC 1.4 User manual

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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Standalone Plasma Torch Height Controller
Model: THC 1.4
INSTALLATION OPERATION
MANUAL
RELEASE 1 – OCT 2015
Nasik, India
www.ntengineers.in

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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SAFETY ADVISE / WARNING
WHEN THE DEVICE IS IN OPERATION, HAZARDOUS VOLTAGES WHICH CAN BE
FATAL TO HUMAN LIFE ARE PRESENT INSIDE THE ENCLOSURES AND AT THE
CONNECTION TERMINALS. PLEASE FOLLOW PROPER SAFETY WHILE
HANDLINE AND INSTALLING THE EQUIPMENT.
Touchi g live electrical parts ca cause a fatal shock or severe bur . Operati g
the plasma system completes a electrical circuit betwee the torch a d the
workpiece. The workpiece a d a ythi g touchi g the workpiece are part of the
electrical circuit. Never touch the torch body, workpiece or the water i a water
table whe the plasma system is operati g. I stall a d grou d this equipme t
accordi g to the i structio ma ual a d i accorda ce with atio al a d local
codes.
Before removi g a y power supply or system e closure cover, disco ect
electrical i put power. Wait 5 mi utes after disco ecti g the mai power to allow
capacitors to discharge.
Never operate the plasma system u less the power supply covers are i place.
Exposed power supply co ectio s prese t a severe electrical hazard.
Whe maki g i put co ectio s, attach proper grou di g co ductor first.

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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Overview
DigiCut THC is a automatic plasma torch height control/initial height sensing system designed for
conventional plasma cutting applications on an X-Y cutting table. The system uses the raw plasma arc
voltage to control the physical stand-off distance) between the torch and work piece during plasma arc
cutting. Initial Height Sense IHS) is accomplished by ohmic contact sensing or by a floating switch
method. The THC has been designed and optimised for conventional air plasma systems.
DigiCut THC systems includes the following components
MAIN THC UNIT
The Main THC Unit houses a microcontroller, a HMI with a Backlit Graphic LCD Display, LED's for
Status and buttons. The Main THC unit is the heart and control centre of the entire THC operation. The
Main THC unit interfaces with the CNC Machine, Plasma Power Supply, Voltage Divider Unit, Ohmic
IHS Unit through discrete IO connectors.
VOLTAGE DIVIDER UNIT
The voltage divider unit provides a filtered and isolated low voltage signal which is derived from the
actual ARC voltage of the Plasma Arc voltage. The unit receives raw arc voltage from the plasma
power source. Special care and safety precautions should be taken and the unit must not be touched or
handled while the plasma is in operation. The unit enclosure must be properly grounded to ensure
personnel safety. The unit can be mounted near to the plasma power supply.
OHMIC IHS UNIT
The unit provides Ohmic sensing contact sensing) capability with isolation to the Main THC Unit. The
unit has connections to AC power, Main THC Unit and the Work Job) and the Shield Torch). Special
care and safety precautions should be taken and the unit must not be touched or handled while the
plasma is in operation. The unit enclosure must be properly grounded to ensure personnel safety. The
unit can be mounted near to the plasma power supply.
OPTIONS (NOT INCLUDED IN STANDARD ORDER)
1. LIFTER ASSEMBLY WITH MOTOR & DRIVER
2. FLOATING SWITCH BASED TORCH HOLDER ASSEMBLY

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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Features
DigiCut THC Plasma Height Control is an automated height control system for automated plasma
cutting applications. This product uses microprocessor technology to automatically detect the plate and
adjust torch position to an arc voltage set point during plasma cutting operations. This reduces operator
input, improves accuracy and increases productivity.
Features
•DigiCut THC is Fully standalone and can be used with any CNC Controller
•Easy setup and Operation
•Automatic & Manual Operation Modes
•Microprocessor based for increased sensitivity and control
•Graphic LCD display for set/actual voltage display, parameter settings
•Stepper / Servo motor based Z Axis control for higher precision & accuracy.
•Provides ISOLATED STEP & DIRECTION signals for Stepper / Servo Driver. Driver Not
included)
•Dual Speed IHS Initial Height Sensing) for both Ohmic and Floating.
•Adjustable pierce height and cut height in 0.1 mm intervals
•Adjustable pierce delay in 0.1 sec intervals
•LED outputs for easy status indication for Cut, Up, Down, Plasma start, Motion Start, and Auto
/ Manual.
•Host of Settings for fine tuning system operation.

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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Specificatio s
Compatible Motors
Stepper or AC/DC Servo based on position mode of operation
Step & Direction Signal)
Operating Voltage
Main THC:
24V DC
±5%
Voltage Divider: 240V AC ±5%
Ohmic IHS: 240V AC ±5%
Standard lifter range:
Based on lifter design
Motor output:
STEP & DIRECTION PNP
+5V SIGNAL and GND Outputs
MAX OUTPUT RESOLUTION
0.01mm
ACCURACY
±1 Volt
Voltage control range
45 to 220 VDC
Pierce Height
1.5 to 9.9 mm User Adjustable)
Operator switches:
UP / Down
Auto / Manual
IHS Auto / Manual
HIS Test / Arc Test
Pierce Delay
Pierce Height
Cut Height
Settings
LED Status Indication:
POWER
CUT
PLASMA
MOTION
UP / DOWN
AUTO / MANUAL
IHS AUTO / MANUAL
Operating environment:
0 to 50C;
95% relative humidity non-condensing)

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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Physical Dimensions:
Main THC Unit
192mm width
96mm height
100mm depth

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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Pa el Cut-out Details & Dime io s
Fro t View of Fitti g with Dime sio s

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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Side View of Fitti g with Dime sio s & Cleara ce Details

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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MAIN THC U it – Fro t Pa el
Pierce Height
Control from
1.5 to 9.9mm
Pierce Delay
time from 0.1 to
3 Seconds
Cut Height
Adjustment
Interface buttons
for Up/Down,
Auto/Manual,
Settings and
HIS/ArcTest and
LED Indications
LCD Display for displaying the Currently
set values and various status displays
during operation.

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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Co ectio s
MAIN THC UNIT
1.
DC S
u
p
ply Port 2Pi
24V DC Supply should be connected through an external
SMPS. SMPS of minimum current rating of 2A should be
used for 100% duty cycle of the THC. To Avoid interference
use a sepeate SMPS for THC operation only. Do not share
this SMPS with any other loads. PLEASE DO NOT
CONNECT REVERSE POLARITY TO AVOID DAMAGE.
2. Motor Outputs: 3 Pi
(GND, DIRECTION+,PULSE+)
This is 5V Signal output for driving Stepper or Servo Motor
for the Z axis operation.
3. PLASMA INTERFACE CONNECTION (4 Pi )
PREFLOW
PREFLOW
This is the switch DRY CONTACT) output for starting the
Plasma Preflow operation before pierce. If you plasma power
supply does not support preflow then please leave this
unconnected.
ARC START
ARC START
This is the switch DRY CONTACT) output for starting the
ARC of your Plasma Cutter. Please refer your plasma power
source manual for more information of connection to your
power supply.
4.
CNC IO Co ector
This contains all the signals required
for interfacing with your CNC
Controller. All the signals are isolated
and operated with 24V signal.
CNC-COMMON can be set as + or –
by setting the jumpers inside the main
THC Unit. The 4 CNC signals CNC-
CUT, CNC-CORNER, CNC-UP, CNC-
DOWN are used with CNC-COMMON
input. Default setting of CNC-
COMMON is +, so the 4 signals are
operational when –24V is supplied to
each one of them.
OK TO MOVE 2 Nos) is a dry contact
switch output for starting the motion of
your CNC Controller. Please refer
manual of your CNC Controller for
interfacing this signal with your system.
All other signals are switched by +24V.
Down Limit, Up Limit, Collision,
Plasma Arc Transfer)
+24V and GND is also available at the
CNC IO Connector.

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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5
.
OHMIC
IHS
Co ector
This connector is used to interface the OHMIC IHS Box with
the Main THC Unit using the supplied cable.
6. Power Switch
This switch is used to Power On / Off the main THC Unit.
7. DC Supply Port 2Pi (3 PIN)
Middle pin should be left unconnected. Please loop the power
supply given on 1) with this Port.
PLEASE DO NOT CONNECT REVERSE POLARITY TO
AVOID DAMAGE.
8. USB Port
This port is used to update the software of the THC Unit.
9. ARC Voltage INPUT
This port if used to connect the divided and isolated ARC
Voltage with the Voltage Divider Box using the supplied
cable.
10. Grou d (Earth)
Please supply ground / earth on this screw. Earth resistance should be ideally be less than <1 Ohm for smooth
and trouble free operation.

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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VOLTAGE DIVIDER UNIT
1. AC 230 V Round Circular 3 pin connector)
2. DB9 – Divided voltage output. Connect to main THC unit using supplied cable.
3. Screw Terminal for + and – raw arc voltage

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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OHMIC IHS UNIT
1. AC 230 V Round Circular 3 pin connector)
2. DB9 – OHMIC IHS Signals
3. Screw Terminal for GROUDN and SHIELD
WARNING! For safety and proper operation all three units must be connected
to the star ground on the work table.

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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LED Diagnosis OF Ohmic IHS Unit.
Cut D8 D7-IHS D4 Description
On If D8 turns on that means IHS board is getting 2 V from THC, if NOT check 2 V supply to THC DB25 Pin 18,19,20
Off On If D turns on when Work&Shield Shorted means 230V
present on IHS Board, CU
T led should be OFF to test this
Off On On On
If D and IHS Turns on when Work&Shield shorted means
230V & 2 V Present and board working Ok, Ohmic=1 shold
show in diagnosison THC
On On Off Off
If Cut LED is ON then Ohmic will not work even when
Work&Shield is shorted. This is for protection. Press down
momentarily or IHS to disable this LED and enable ohmic
again. L15/Ohmic LED inside the THC should glow when
Work&Shield is shorted

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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MAIN THC SIGNALS
I/O Co ector – DB15 Female
All signals to and from the CNC are connected to the DB15 Female connector on
the MAIN THC Unit.
I puts from CNC
CMC-Common
CNC-Start Signal
CNC-Corner Signal
CNC-Up Signal
CNC-Down Signal
CNC-COMMON can be set as + or – by setting the jumpers inside the main THC Unit. The 4 CNC
signals CNC-CUT, CNC-CORNER, CNC-UP, CNC-DOWN are used with CNC-COMMON input. Default
setting of CNC-COMMON is +, so the 4 signals are operational when –24V is supplied to each one of
them.
[All above inputs are isolated and are driven using 24v + or -) signals from CNC]
To change the CNC-COMMON from + to – please set the jumpers inside the THC box as given
below

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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Outputs to CNC
Ok to Move Motion)
[Ok to Move is a dry contact relay output signal. Any voltages that the CNC required should be
supplied externally]
Other Sig als
Floating Switch Input Float+ and Float-)
Up Limit Input+
Down Limit Input+
Collision Input+
Plasma Arc Transfer+
+24V Supplied from Input)
GND 24V) Supplied from Input)
[All inputs are opto-isolated and are driven using 24V DC Signals]
MOTOR OUTPUT – 3 Pi Screw Type Termi al
GND
Step/Pulse +
Direction +
[Motor output is isolated PNP type and voltage level is 5v DC to be connected to suitable
Stepper/Servo Driver]

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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MAIN THC SETTINGS
QUICK ADJUST SETTINGS
Butto s
1. Pierce Height
This button lets you adjust the pierce height by turning the knob. You can press the IHS button
to see the height adjusted.
2. Pierce Delay
This button lets you adjust the pierce delay by turning the know. The THC will wait for this delay
before issuing motion signal to the CNC for starting the cutting operation.
3. Cut Height
This button lets you adjust the cut height. This is the distance the torch would move down after
pierce is complete and then the arc voltage height control kicks into action.
BUTTONS
Up / Dow
This lets you JOG the Z axis during idle. The Z DRO on the LCD would update giving you the
precise location of the Z axis.
During cutting in Auto Mode this lets you dynamically adjust the Target Set Voltage.
During cutting in manual mode this lets you JOG the torch in fixed intervals of 0.5mm for each
press.
Auto / Ma ual
This lets you change the THC mode of operation from Manual to Auto and vice versa.
In Auto mode the THC works by maintaining the voltage by continuously adjusting the Z Axis. If
the THC does not read sufficient voltage after pierce it would not start the cut and show ARC
ERROR. Also UP/Down pressed during the cutting operation would adjust the SET voltage
dynamically and the operator would hence see the maintained height change proportionally.

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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This feature is particularly useful when the operator does not have knowledge of the exact
voltage to be set for the Plasma source and can adjust the voltage by observing the distance
and adjusting it during cutting.
In Manual Mode the THC does not correct the height of the torch during cutting. It merely
displays the actual ARC voltage for reference. This could be used to see the ARC voltage for
sample cutting on straight surfaces. Also UP/DOWN pressed during cutting in manual mode
will JOG the torch up and down for fixed distance of 0.25mm for each press. The THC would
also issue motion signal even if the valid ARC voltage is not available from plasma.
IHS / Arc Test
IHS
The IHS button performs initial height sensing. This is used to reconfirm the pierce height at
this the plasma would be turned on. Plasma manufactures specify this height. Pressing the HIS
button again when the torch is at pierce height retracts the torch to the retract height specified
in the settings.
ARC TEST
Pressing the HIS button for 3 seconds continuously enables you issue PLASMA START signal
to the Plasms Power Source. The signal is issued for as long as the button is pressed. This
enables you to verify the plasma start wiring and the arc voltage connections. The LCD would
display the actual arc voltage when the plasma is started.
SET
The THC allows various parameters to be tunes. The SET button enables uses to enter the
settings menu to fine tune these various settings.
Pressing the SET and the IHS buttons in the settings menu allow you to move to difference
settings available in the system.
Pressing the SET button while in settings saves the changes made and exits to the Main
Screen Of the THC.
The brief of all the settings available in the THC is given below.
1. Cut Voltage
This is the target voltage the THC maintains by moving the torch up/down on a continuous
basis. This can be adjusted by the UP / DOWN button in 0.5 V increments.
2. Deadba d
The system allows you to adjust the dead band between 1v to 15v. This is basically the voltage
band for which the THC will not take corrective action. For example: If the target voltage is

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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140v and the dead band is set to 2 volts then the THC would not move the torch when the
actual voltage is between 139 to 141 volts. Only once the voltage cross this band the correction
would take place. This is used to avoid over corrections in the THC.
3. AVC Respo se time
This is the time in milliseconds that the THC averages the ARC voltages
and then takes action. If the cutting speed is high then this time should be
kept low for quick actions. If the cutting speed is slow this should be kept
higher. This setting can also be fine tuned by observing the THC during a
cut and then increasing or decreasing the THC response time accordingly.
4. Float Sw Offset
When the Initial height sensing is done by floating switch instead of ohmic,
most lifter designs over travel a bit after the torch touches and before the
floating switch triggers. This over travel can be compensated by raising the
torch by the
Float Sw Offset + Pierce height
when the IHS operation is done using the floating switch.
This ensures the same pierce height is maintained irrespective of the HIS
being done by Ohmic Sensing or the floating switch mechanism.
5. Float I put Logic
The floating input connection logic can be changed from Active High to Active Low using this
setting. This setting is available to accommodate different lifter designs and floating
mechanisms being used by difference manufactures.
6. Float as Collisio
The floating switch can be used as a collision signals when this setting is enabled. The THC
would withdraw the Plasma Start and Ok to Move Motion) Signal to stop the cutting if this
setting is enabled and the floating switch is triggered during the cutting operation.

PLASMA THC 1.4
INSTALLATION & OPERATION MANUAL
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7. LCD Update Time
This setting lets you adjust the time frequency in milliseconds that the data on the LCD is
refreshed on the THC LCD Graphic display.
8. Z Speed
This settings lets the user adjust the Z axis speed in mm/ second.
9. Z Acceleratio
This settings lets the user adjust the Z axis acceleration in mm/ second/second. This can be
kept high or low as per the lifter design.
10.Slow IHS at
The system supports dual speed IHS. This helps prevent damage to the torch by hitting the
plate at the full speed of the Z axis. This settings lets you adjust the distance at which the slow
HIS is started. The THC assumes the last IHS location to be the 0 point. For example: if this
setting is set to 15mm and the slow IHS speed is set to 50% the torch would slow down at
15mm to 50% of the set speed.
11.Slow IHS Speed
This is the speed in percentage of the main THC speed that the THC would slow down to
during performing the IHS operation in dual speed.
12.E able Ohmic HIS
This settings is used to ENABLE / DISABLE the ohmic based IHS.
13.Partial Raise Ht
This is the distance in mm that the torch is raised after each cut is over. This helps to avoid the
torch hit the cut parts during traversing to the next cut location.
14.Full Retract Dly
This is the time in seconds that the torch would be retracted fully till the up limit is triggered if no
activity is performed Idle).