Electronic Engineering Schematics
Production and Calibration of Controller
Production Checklist of STC1000
An analog temperature controller is not very easy to make. It is
used in tough industrial environment and has to perform with
reliability and accuracy on continuous operation.
- Has Transformer been soldered properly with reinforced
pads - Scrape with blade area around pad and make
lead bridges to support transformer.Front Card and Rear Card
must have very thick solder bridges after fixing sq. post.
- Is the Front and back stickers and SL. No Sticker
properly stuck - In Front Sticker the holes for
switch, pot LED etc. must be without Burrs file and improve.
Acrylic should not have cynoacralate stains. In the back
sticker there should not be any wrinkles use rubber solution
(fevibond) to stick properly.
- Are all the Threaded parts and Plastic parts fixed with
fevibond - Use Fevibond (very little) for the CJ box
in rear panel all Metal screws and loose mechanical parts in
Pots, plastic threads and pillars. This prevents parts from
breaking loose during transportation or vibrations, All Nuts
/ Bolts fix tightly .
- Are all the Pots. Turning freely and is direction
proper - Clockwise is always increment or increase in
a parameter and anti-clockwise is decrement of any control
or parameter. All pots should turn without friction.
- Are all the Front panel components Fixed properly - All
Four Displays are required Fourth is for Overrange and
Polarity. LED’s are for Load On or Process on and Should be
neatly visible above sticker and Switch should not get stuck
after cabinet is closed and screwed.
- Only two screws must be visible on the back panel -
Cover Pot clamp screw, card fixing screw etc. by Black
insulation tape.Use Ni. plated Phillips / Universal head
Screws for fixing back plate.
- Are all other items in the final packing - Check
by fixing both side clamps and file if required add
Instruction manual in Cover or with Invoice and DC.
- Sources of omissions and neglect checked by Visual
Inspection - Gnd to Earth Capacitor to be added
0.01uF 103 1kV, Polarity of Electrolytic and diodes ,
Regulator tab touching any conductor, Loose wire strands,
Solder Bridges absent at places where it is required.
- Troubleshooting when a card does not work - Keep
always a 3D reference of a working unit / card compare
component to component by visual inspection wrong polarity
of diodes / Tx / IC, wrong value of Resistor or Low value
capacitors missing jumpers solder bridges or hairline shorts
at edge of board or pad to pad lead streaks.
4-20mA Loop-Powered System
Calibration and Testing Procedure for STC1000P Proportional
Power on unit and leave for 15 mts
1-Wire Temperature Control
Calibration Of Room Temperature Preset And Full Scale
Feed 0.00 mV to the TC input using a millivolt source and adjust
P1 (PR1) Z for Display to read Room temperature as shown by a
Feed mV corresponding to maximum temperature and adjust P2 (FS)
for Display to read full scale temperature. Verify Room
temperature again by feeding 0 mV repeat three iterations till
the Zero and Full-scale readings are set to Room temp (RT) and
FS temp + RT respectively.
e.g. If room temp. is 26 deg. C and as per tables 0 mV is 0 deg
C and 16.39 mV is 400 deg C for K type then feeding 0 mV we
should read 26 deg C on TC and feeding 16.39 mV we read 400 + RT
i.e. 426 deg C.
||Reading on TC
|| 0.00 mV
|25 % FS
|50 % FS
|75 % FS
Testing of Proportional Control and Settings.
Adjust Setpoint to Read 300 deg C, Feed mV for unit to read same
PV. Set Proportional Band to MIN fully anticlockwise till end
If Process ON Led in ON turn anticlockwise till it just turns
OFF or flickers. If Process ON Led in OFF turn clockwise till it
just turns ON or flickers. Now the error cal is calibrated at
300 deg C (for other temperatures it may differ)
Set Proportional Band to MAX fully clockwise till end (000 Zero
Ohms). (Now SP must be at 300 and PV must be at 300). Now LED
will turn ON for 5 Seconds (approx.) and OFF for 5 seconds for
10 Sec cycle time for shorter cycle times just observe
Decrease mV (PV) till LED turns fully ON no flickering note this
Value T1. Increase mV (PV) till LED turns fully OFF no
flickering note this Value T2. T1 is lower end of PB and T2
upper end T2 - T1 = PB i. e. the Prop Band .
e.g. T1 = 295 T2 is 305 305 - 295 = 10 hence PB = 10 deg C.
Verification of Relay operation.
Danger ! DMM is in Ohms Mode, Even if one probe touches 230 V
DMM is Gone, so take extra care while doing this test probe
only relay contacts.
|RESISTANCE “NO” TO “C” in Ohms
|GET RELAY TO TURN ON
|GET RELAY TO TURN OFF
For Pulse Output model for SSR e.g. STC1000KPP Use a DMM 20 V
mode to observe 12V DC when Process ON and 0 V when Process off.
Process ON ............. V Process OFF
Earth and isolation and safety related tests..
Off Unit before this Test
|GND TO EARTH RESISTANCE
|TRANSFORMER RESISTANCE L to N
|WINDING TO EARTH RESISTANCE L to E
|CHASSIS TO EARTH RESISTANCE
General Checklist to ensure optimum quality.
- DOES LED TURN ON WHEN RELAY IS ON AND VISE VERSA
- DOES DISPLAY READING JUMP WHEN RELAY OPERATES ............
- SCREWS LOCKED WITH ADHESIVE, POTS TURN SMOOTH.
- ARE ALL STICKERS STUCK PROPERLY WITHOUT FOLDS ............
- HAVE EXTRA HOLES AND SCREWS COVERED BY B TAPE ............
- HAS THE SENSOR POLARITY BEEN MARKED WITH PAINT
- HAS THE DB / PB KNOB MARKED BY A WHITE PAINT LINE.
Operation of displays and Controls.
Related Documents in PDF Format
- Note SP Min ................ SP max ...........
- Note PB Min ................ PB max ...........
- Feed mV for display to read 1234 Counts reading
- Feed mV for display to read 345 Counts reading
- Feed mV for display to read -456 Counts reading
- Feed mV for display to read 1xxx Overrange rdg.
- Verify Decimal Point has been connected record in this
> 1 9 9 9
- Display should have uniform brightness without modulation.
- Process ON LED must be bright and Visible outside.
- Push-button switch should not get stuck on repeated
Back to Process Control
30th Aug 2020