Unigas HRX2050R, Service Manual

Page: 101 / 120

RECOMMENDATIONS FOR LMV5x CONNECTIONS
Connections affected by EMC noises are related to the bus cable (actuator line cable,
PLL52), detection probe cable, speed sensor cable, 4-20mA signal cable that controls the
VSD.
Input and power cables (400V e 230V) must be laid separately from the signal cables.
The bus cable between control panel and burner and between burner and PLL52 board
(used when O2 trim control must be perfomed) must be laid separately and far from power
cables.
When long cables must be provided, it is recommended to put the bus cable into a pipe or
a metallic sheath: the sheath ends must be grounded with suitable rings.
Provide a shielded three-pole cable type T (see Annex 1), between VSD
and motor; earth must be outside the shielding.
Shielding must get to the lower part of the VSD and get to the motor junction box.
Shielding must be connected to the equipotential ground on both ends, better with suitable
rings.
Otherwise, a standard cable can be used also but put inside a pipe or metallic sheath (the
sheath ends must be grounded with suitable rings) and an earth external wire for the motor
ground.
The cable for the 4÷20mA signal that controls the VSD, must be shielded, only LMV5x
side ends connected to the equipotential terminal. If the VSD is not inside the control
panel, the cable must be laid separately inside a metallic sheath earthed by means of
rings.
As for the speed sensor cable and QRI detection probe cable, provide a “Ethernet “ cat.5
or 6 cable, inside a metallic sheath (with ends earthed by means of rings) and laid
separately from the motor cable.
As the sensor uses three wires, divide and twist the pairs to avoid noises.
Alternatively, provide a 3x2x0,50 twisted cable Liycy type (see Annex 2).
In case of O2 trim control version, O2 probe and PLL52 board must be connected by
means of a 3x2x0,50 twisted cable Liycy type (see Annex 2).
NB:
when a shielding has both ends wired to Earth, be sure they are at the same potential.
If there is any Voltage difference, ground just one of the two ones, generally the one
closest to the weakest, respect to EMC, component. Anyway give way to the burner
control, that is wire to ground the end of the shielding closest to the LMV.
For instance, the cable between LMV and VSD, if the shielding has only one end wired to
Earth, this one has to be the one LMV side.
COD. M07979CD rel. 3.2 01/13