Top Cable ROZ1-K, the power supply cable for motors with VFD drives

Top Cable’ s TOPDRIVE® ROZ1-K cable design is the one with the highest performance, favouring earth leakage and avoiding the effect of voltage peaks:

Flexible copper conductor (class 5), which gives the cable maximum flexibility.
Arrangement of conductors and earth three plus three (3C+3G) to avoid current leakage through earth.
Cross-linked polyethylene insulation (XLPE) with performance far superior to PVC.
Double aluminium-polyester screen that offers 100% shielding and thus prevents the emission of electromagnetic waves from our cable to the rest of the equipment.
Tinned copper braid, with anti-corrosion features and better installation.
Halogen-free outer sheath (LSHF) with the highest CPR classification (Cca – s1a, d1, a1) with low emission of fumes and corrosive gases in case of fire to protect people and equipment.

This is why Top Cable’s TOPDRIVE® R0Z1-K cable is recommended by leading manufacturers of variable frequency drives and also by GAMBICA, the British Capital Goods Association.

A cable with an inadequate shield (or no shield) can act as an antenna and be a source of radiated emissions. Unshielded cables do not guarantee electromagnetic compatibility and impedance matching, and are therefore not suitable for powering VFD motors.

Similarly, it is not advisable to install single core cables, even if they are shielded, as it is necessary to compensate for inductions and respect the symmetrical configuration of the 3C+3G phases particularly in higher current applications.

A Variable Frequency Drive (VFD) is a system for controlling the rotational speed of an alternating current (AC) motor by controlling the power frequency supplied to the motor.

An electric motor rotates its rotor according to the parameters achieved by the voltage and frequency of the electrical power supplied to the motor. Internationally, there are different mains voltages, such as 400 V (three-phase), 380 V (three-phase), etc., and frequencies of 50 or 60 Hertz. By varying the voltage and/or frequency, the performance of the motor, including the speed, varies. It is usually difficult to change the voltage or frequency without auxiliary equipment.

To vary the voltage and frequency effectively, a variable frequency drive is used. Normal power is supplied to the VFD and the output of the VFD is fed to the electric motor. The VFD has controls that can be adjusted to control the speed of the motor.

A VFD provides precise control of the speed and torque of an AC motor through pulse width modulation (PWM). In a VFD system, it is critical to choose the right cable for best performance, maximum energy efficiency and long life.

TOPDRIVE® R0Z1-K cable has been designed according to the IEC 60502-1 / IEC 60092-353 reference standard and complies with the European CPR (Construction Products Regulation) Cca – s1a, d1, a1. In addition, the TOPDRIVE® R0Z1-K cable is CE / UKCA / BUREAU VERITAS / DNV-GL / ABS /LLOYD’S REGISTER / RoHS /.

Flame non-propagation according to UNE-EN 60332-1 / IEC 60332-1.
Fire non-propagation according to UNE-EN 60332-3 / IEC 60332-3 and EN 50399.
CPR reaction to fire: Cca-s1a, d1, a1, according to EN 50575.
Halogen-free according to UNE-EN 60754-1 / IEC 60754-1.
Low emission of corrosive gases according to UNE-EN 60754-2 / IEC 60754-2.
Low smoke emission according to UNE-EN 61034 / IEC 61034:
Light transmittance > 80%.

The standardised identification of the insulated conductors of the TOPDRIVE® R0Z1-K cable is as follows:
3 x + 3 G: Grey + brown + black + Yellow/Green (3G) (from 6 mm2).
4 G : Grey + brown + black + Yellow/Green (up to 4 mm2).

Certain precautions must be taken during installation:

Always respect the bending radius of the cable. Radii smaller than the minimum indicated may cause damage or breakage to the outer sheath.
Adequacy of the laying. The cable must be laid carefully, taking care not to damage the cover in irregular areas, sharp edges, etc.
Fixings/Fastenings. Adapt the fixings so that the cable adopts a natural position in the laying to avoid stress concentration on the roof. Allow a certain degree of freedom of movement and avoid excessively tight cable ties.

To avoid voltage peaks, we should use a cable with XLPE insulation (90ºC) instead of one with PVC insulation (70ºC). In addition, the dielectric coefficient of XLPE (2.3) is much lower than that of PVC (7.4), which also reduces the capacitive effect and therefore the magnitude of the reflected waves.