Flintec KP-4 - Manual (Page 4)

Junction Box Type KP – Technical Manual, Rev. 1.00 August 2007 Page 4 of 4
After all conductors have been soldered to the printed circuit board, the cable glands must be tightened.
Please verify that all cable glands are tight and the cable is fully stress relieved.
Important: To prevent any deterioration of the signals it is recommended to clean the printed circuit-board
from splash of solder, colophonium, grease and other dirt after the soldering works have been finalised. Use
spirit or similiar.
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 / Solder joint 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 solder points straight below the channel designation 1...4 shall connect the solder joints for the
resistors to be installed afterwards (shipment status). Otherwise the load cell will not get powered.
2. 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.
3. 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”.
4. 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 Ω Ω 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 Ω Ω Ω = 0.8 Ω
5. Remove the solder of the corresponding solder point straight below the channel designation 1...4.
Otherwise the correction resistor to be installed would get short-circuited and would stay useless.
6. Install the correction resistor on the printed circuit-board for the corresponding load cell (the solder joints
are located on one line right and left to the channel designation 1..4).
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).
Clean the printed circuit-board again after the corner correction has been succesfully finalised. 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.