Emotron CDU/CDX 48-008 [10/82] Six golden rules for switchgear cubicle design

EMOTRON DSV 5445/5444

Page 10

 Emotron 21.04.09

4 Connection of frequency converter

4.1 Installation instructions

"Six golden rules for switchgear cubicle design"

1) Keep the "24V systems" (or any other low voltages) separate from the "230V systems" or "400V

systems"!

2) Take care that the three basic voltages mentioned under 1) must be routed star-wise from their

sources to the individual loads! Especially the "24 V system" is critical in this respect. Never wind

the 24 V or 0 V lines through the bus bars and load points! Always lay new cables from the star

point for each bus bar or load group. The star point in the "24 V system" is the power unit or

smoothing capacitor in the 24 V source! Provide a distribution connector for this purpose for the

corresponding voltage to allow star supply.

3) The screening of all screened cables (these are normally cables from the converter to the motor

- if no add-on filter is employed - and the cables to the brake resistor and to the rotary encoder

system) must always be connected at both ends! The rotary encoder must also be connected to

the motor earth potential, i.e. be connected internally to the screen. On long lines, it can become

necessary to repeat this every 25 m, if a suitable earthing point is available. The only cables to be

screened at one end (always at the source end) are analogue set points (0...10V, 0...20mA or

4...20mA).

4) Suppress interference at contactor coils with associated RC elements or varistors. Also pay

attention to the electromagnetic valves and brakes! An omitted varistor (which is selected to suit

the nominal input voltage at the braking rectifier, i.e. for 230 V AC or 400 V AC) in the brake

terminal box (or at the supply terminal in the switchgear cubicle) impedes the function. The RD, RC

or varistor elements must be connected directly to the seat of the coils. If this is not possible, the

cable must be screened at least as far as the possible seat of the suppression element.

Unsuppressed inductances cause radio interference and high transient over voltages during

switching. The result can be unexpected function and defects, which can affect your entire system.

5) Provide sufficiently large cross-sections especially for "0 V" and "protective earth"! All supply

cables to DSV544 and DSV545 may not be looped to other loads! All supply cables to DSV544

and DSV545 may not be looped to other loads. - see next paragraph). It is not permitted to change

from a 4-wire to a 5-wire system and vice versa within an installation branch, which can lead to

undesirable EMC problems. If you wire the lift cubicle with 4 conductors, the separation to 5

conductors may be performed only directly in the cubicle.

• Use our add-on filters that are available for the DSV544 and DSV545 systems. The add-on

filter is a power mains and motor filter in one unit and can be used at a distance of 10

metres without screened cables. The normal external power supply filter cannot dissipate

reflection power. Reflection power is the term used to describe an interference source that

is often underestimated, and which arises only after screening. This capacitive energy must

drain away, which is often impossible when earthing points are too far away or earthed at

too weak earth points.