What you should know p Environmental conditions of installation : - minimum and maximum ambient temperatures - external influences, dust, corrosion, etc. p Run layout. p Characteristics of the load(s) to be fed : - power consumption and permissible voltage drops - current drawn and permissible voltage drops on starting according to set rules for full load motor starts (particularly in the case of hoisting). p Conditions of use : - coincidence factor of load operation (in the case of several loads) - use factor. Study methodology p Confirm the compatibility between environmental conditions and busbar trunking. p Determine the nominal current rating Inc of the trunking as a function of the operating current Ib : - motor start-ups under low load (see below) - motor start-ups under full load (see pages 11051/6 and 11051/7). p Confirm rating selection on operation as a function of permissible voltage drop : - motor starts under low load (see below) - motor starts under full load (see pages 11051/6 and 11051/7). p Select and locate the run lengths (see pages 11051/8 and 11051/9). p Determine the nominal current In of the mobile connection(s) (see page 11051/10). Busbar trunking selection for starting motor under low load Application : machine-tools, small loads, hand tools, etc. p Select the nominal trunking rating : this must be at least equal to the operating current In busbar trunking Ib - Feed for a single load Ib = In load - Feed for several loads Ib = In loads x k (operation coincidence factor) p Confirm the condition of maximum voltage drop : U 2.5% (1) by using the following formula : U = ZlbL 3 where : U = voltage drop, in volts Z = mean impedance per conductor L = run length in metres. (1) Half of the total 5% permissible voltage drop (NF C 15-100 tab 52J) is usually attributed to the feed cable; the other half to the KXA trunking. Schneider Electric 11051 Ver4.00-EN.fm/
Busbar trunking selection for starting under full load (simplified method) Supply to hoisting or similar equipment is characterized by the need to limit the voltage drop in order to preserve power and maximum torque. Therefore selecting the trunking rating is normally a function of the maximum permissible voltage drop on starting. The selection curves which follow, take into account a total voltage drop of 10 % on starting, of which half is attributed to the trunking KXA (5 %), and half to the feed cable. Refer to the general method on page 11051/7 for various characteristics. Selection of the trunking rating KXA (Inc) The current carried by the busbar trunking (Inc) depends on the number of concurrent movements. p A single movement (controlled by pendant control station). The current Inc must at least equal the nominal current of the most powerful motor. Inc In hoisting motor p Several concurrent movements (controlled by switch box). The nominal current Inc must at least equal the total of the nominal currents of the two most powerful motors. Inc In hoisting motor + In 2nd most powerful motor Check, by using the curves below, that the length of the line is not excessive for the selected rating (should it exceed the limit, see pages 11051/7, 11051/9 and 11051/10). p For equipment fitted with direct start motors, use diagram 1. p For equipment fitted with rotor start motors, use diagram 2. Diagram 1 (direct start motor). 1 KXA-05 2 KXA-06 3 KXA-10 4 KXA-12 5 KXA-16 Length of run in m Rated current of the trunking Example 1 : feed a travelling crane controlled by pendant control station, fitted with : p 1 hoisting motor of 18.5 kw with direct start, p 1 translational motor of 7.5 kw with direct start, p 1 steering motor of 1.5 kw with direct start, fed with 400 V. In this case Ib = In hoist, i.e. 35 A. Curve 2 shows that KXA-06, rating 60 A, is suitable for a run of approximately 40 m. Choose KXA-10, 100 A rating for a run of between 40 m and 70 m. Starting current (Id = 6 In) Diagram 2 (rotoric start motor). 1 KXA-05 2 KXA-06 3 KXA-10 4 KXA-12 5 KXA-16 Length of run in m Rated current of the trunking Example 2 : feed a travelling crane controlled by a switch box, fitted with : p 1 hoisting motor of 22 kw with rotor start, p 1 translational motor of 11 kw with rotor start, p 1 steering motor of 2.5 kw with direct start, fed with 400V. In this case Ib = In hoist + In translation, i.e. 63 A. Curve 2 shows that KXA-10, rating 100 A, is suitable for a maximum run length of 90 m. Starting current (Id = 2.5 In) 1051 Ver4.00-EN.fm/6 Schneider Electric
Busbar trunking selection for starting under full-load (general method) Rating selection must take into account the actual characteristics of supply and use. It is usual to base it on the permissible voltage drop on starting and in a steady state as indicated by the manufacturers. For hoisting applications, if more precise information is not available, use the following as a guide : p 10 % on starting, i.e. 40 V for a 400 V network. p 5 % in steady state, i.e. 20 V for a 400 V network. Calculating trunking rating p Calculating the maximum permissible voltage drop along the KXA trunking at the start, then in a steady state. U KXA = U total - U feed cable p Calculate the maximum permissible impedance in both outline cases, using the following formula U Z = ---------------------------------------- 3 l L 10 3 where : Z : Impedance per phase in mω/m. U : Compound voltage drop, in volts. I : Absorbed current in A. L : Length of the run or section length, in meters. Only the lowest Z impedance should be used (Z at the start or Z in steady state). p Then, using the table below, select the value for Z which is immediately below the value obtained in the calculation. s The rating to be retained corresponds to the result from the previous calculation. Z mω/m 1.890 1.258 0.787 0.585 0.375 Type of trunking KXA-05 KXA-06 KXA-10 KXA-12 KXA-16 lnc trunking A 50 60 100 120 160 Application example A KXA run of 110 m length feeds a motor which draws 35 A in steady state and 90 A on starting, with a 400V supply. The manufacturer gives 10 % permissible voltage drop on starting and 5 % in steady state. The run is fed by U 1000 R02V cables, 4 x 10 mm 2, 42 m long. p Calculation of total permissible voltage drop : - On starting : 10 % of 400 V i.e. 40 V. - In steady state : 5 % of 400 V i.e. 20 V. p Calculation of voltage drop in the feed cable : The voltage drop for 42 m of U 1000 R02V cable, 4 x 10 mm2 is : - On starting : 12.10 V. - In steady state : 4.70 V. p Calculation of maximum permissible voltage drop in the trunking : U trunking = U total - U cable. - On starting : 40-12.10 = 27.90 V. - In steady state : 20-4.70 = 15.30 V p Calculation of maximum permissible Z impedance in the trunking : 27,90 - On starting : Z = -------------------------------------------------- = 1.627 mω/m 3 90 110 10 3 15,30 - In steady state : Z = -------------------------------------------------- = 2.294 mω/m 3 35 110 10 3 The lowest values for Z should be used, i.e. 1.627 mω/m. In the table above, the value for Z immediately below this is1.258 mω/m, i.e. a KXA-06 trunking. Schneider Electric 11051 Ver4.00-EN.fm/
Lengths forming the run Description Symbol Function Distinctive features, suggestions for use Straight length KXA-ppEA4 Basic run section. Length 4 m. On site : - Can be cut (cut the last length of the run). - Reforming a part with length X after cutting : order guide label KXA-16EE. - Reforming a length with the drop. Order jointing unit type KXA-ppJBp. End feed KXA-ppAA4 End of run feed. 100 A maximum (KXA-10). Feed unit KXA-ppBTp 3 uses : - feeds along run, - feeds at end of run (KXA-12 and KXA-16), - feeds section via jumper cable. End cover KXA-16FA Closes the trunking at end of run. Blocked fixing bracket KXA-16ZA2 Mounted in centre of line, it flanges the trunking and directs the expansion towards end of run. See positioning on page 11051/9 Free suspension KXA-16ZA1 Allows the trunking to expand freely. Maximum distance between centres : KXA-05 to KXA-10 : 2 m KXA-12 and KXA-16 : 1.33 m Expansion length KXA-ppGBp2 Absorbs the expansion in the following cases : - long run (L > 120 m), - between ends blocked by curves or trolley entries (L > 30m). Reduces risk of condensation on passing from interior to exterior. See positioning on page 11051/9 Important : To avoid voltage loss, it is essential to use two tap-off units with a 0.6 m gap between them. Curved length KXA-ppERpppX Entry/Exit of mobile connection KXA-ppETppp To follow the precise route of the device being fed. Enables entry/exit of the carrier either manually or automatically during installation procedures : - moving gantry, - transfer with diversion, - dynamic testing. R min. : 0.6 m (KXA05-10) or 1 m (KXA12-16). L min. : 0.6 m ; L max. : 3 m ; Max. angle : 90. Please consult your Regional Sales Office for curves on the vertical Spring mounted carriers are required (horizontal/vertical clearance of 10 mm). Mobile connection KXA-ppCBpp For the connection of mobile loads on a KXA run. Drive force of the mobile connection must be exerted along the longitudinal axis of the trunking. 1051 Ver4.00-EN.fm/8 Schneider Electric
Position of lengths in accordance with diagram Run length less than or equal to 80 m Provide a blocked fixing unit at the centre to direct the expansion towards the end and to avoid slippage. 80 m max. Run length between 80 and 120 m Provide a second blocked fixing unit at the centre of the run. 60 m 60 m 2 m 120 m max. Run length greater than 120 m The run must be divided in to sections of 120 m maximum, joined by an expansion unit (1). Along the run, the sections must include one or two blocked fixing units at the centre, following the rules above. 120 m max. 80 m max. Trunking section placed between two curves p Section with length less than 30 m 30 m max. p Section length between 30 m and 120 m : provide an expansion unit (1) at the centre of the section. 60 m max. 60 m max. KXA busbar extending to the exterior of a building Provide an expansion unit (1), at passage to the outside wall to avoid any risk of condensation. 60 m max. 60 m max. Exterior Interior (1) Important : to avoid any voltage loss, it is essential to use two mobile connections spaced 0.6 m apart to feed the mobile load. Schneider Electric 11051 Ver4.00-EN.fm/
Solutions to limit voltage drop Where the voltage drop is excessive, the number of feed units can be increased to keep the trunking section in line with the current being carried. Here are some examples : U = Z l L 3 = xv.. L U = Z l --- 3 = V 2, 2. U Z l 2 -- L = --- 3 = V 4, 2. U Z l 2 -- L = --- 3 = V 8, 2 Selecting tap-off unit rating Starting motors under low load Applications : Machine tools, small loads, hand tools on a production line Taking into account the load current : In mobile connection In load Starting motors under full load Applications : hoisting motors. The nominal current from the mobile connection depends on : p the number of simultaneous movement commands - a single movement : controlled by pendant control station Take into account the current of the most powerful motor : In mobile connection In most powerful motor - several concurrent movements : controlled by switch box Take into account the total current of the two most powerful motors : In mobile connection 2 In most powerful motor p the type of motor(s) : squirrel cage motors or brush motors, p the type of starting : direct or rotor, p the starting class (1). Using the graph, select In mobile connection : 1 In mobile connection In motor(s) 1 In mobile connection 2 In motor(s) Starting class (1) Starting class : equivalent number of starts for a motor within an hour by involving complete standardized starts and the thermal equivalence between standardized start and standardized pulses or standardized electrical braking. Normally, a pulse equal to 0.25 and braking at 0.8 standardized start. 051 Ver4.00-EN.fm/10 Schneider Electric