Flintec KPK-4 - Manual (Page 4)

O UTPUT C ABLE C ONNECTION
The signal cable (connection between junction box and the following electronics) should be a 6 – wire
shielded cable and has to be kept as short as possible. Because this cable usually has a larger diameter than
the load cell cable, you should use the larger cable gland in the middle of the box. Depending on type and
manufacturer signal cables may have different colours. Therefore make your own choice.
Cable colour, example Description / Terminal designation
outer cable screen = Shield
pink = Signal – (Output –)
white = Signal + (Output +)
grey = Sense –
brown = Excitation – (Input –)
yellow = Sense +
green = Excitation + (Input +)
C ORNER C ORRECTION AT S CALES WITH F LINTEC L OAD C ELLS
Flintec load cells are manufactured with rather tight tolerances, so in most cases an additional corner
correction is not required. The best conditions are achieved if you use load cells of the same class
(Designation is done with capital letters A to I on the load cell package besides the type label).
Hint: Corner errors can have a mechanical background, e.g. sloped mounting surface of the load cell.
Procedure:
1. The jumpers JP1 to JP4 should stay installed. This will disable the potentiometers.
2. The 0 Ohm jumpers instead of the correction resistors must be in place (shipment status).
3. Get the display value for each corner. Use the highest possible display resolution (e.g. factor 10 or higher)
or, if this is not possible, measure the the digital weight increment using corresponding weights.
4. The corner with the lowest display value is the starting point for the corner correction. The differences of
the other corners are calculated with reference to this “basic corner”.
5. Calculate the correction resistance as follows:
Deviation in [kg]
Correction resistance [
Ω] =
Test load in [kg]
X Input resistance of the load cell [
Ω] *
* 1100
Ω input resistance for:
BK2, SB4, SB5, SB6, SB14, SLB, ZLB, UB1, UB5, UB6, PB, RC3
400
Ω input resistance for: RC1, SB2
Example 1: 1100
Ω load cell
0.1 kg corner error with 500 kg test load
0.1 kg
500 kg
x 1100
Ω =
0.22
Ω
Example 2: 400
Ω load cell
10 kg corner error with 5000 kg test load
10 kg
5000 kg
x 400
Ω =
0.8
Ω
6. Install the correction resistor into the junction box instead of the 0 Ohm jumper for the corresponding load
cell excitation OR adjust the potentiometer (see below).
7. Check the corners again. If required repeat the procedure.
Hint: 50 ppm resistors for corner correction are available as a set of 14 values from 0.22
Ω to 4.7 Ω (10 pcs.
for each value; article no. 5200-030).
Correction by Potentiometer Adjustment
The calculated correction resistance is also used as the starting point when the correction is made with the
potentiometers P1 to P4 (25 turns, 10 Ohm Cermet- precision trimmer). When shipped all potentiometers are
in the middle position (appr. 5 Ohm) and disabled by the jumpers JP1 to JP4 (short-circuit). If a potentiometer
shall be enabled, the corresponding jumper JPx has to be removed.
First you have to turn the potentiometer to the clockwise end position (should be a clicking noise). Afterwards
you turn the potentiometer counterclockwise (some turns may be needed until the potentimeter works) until
the computed correction resistance is adjusted. Using an ohmmeter is recommended.
• Use suitable screwdriver!
• Use an ohmmeter
• One turn corresponds to appr. 0.4 Ohm (at end position maybe
some turns are needed until the potentiometer works)
• Clockwise end position = 0 Ohm
• Counterclockwise end position = 10 Ohm
Hints for Poti
adjustment:
• 0 Ohm jumpers instead of correction resistors must stay in place
In the junction box you can also find a dry tablet in a plastic bag. Open the bag and leave the tablet in the
junction box. This will absorb moisture up to a certain degree. Check the cover sealing and install the cover of
the box.
Junction Box Type KPK – Technical Manual, Rev. 1.01 June 2009
Page 4 of 4