Introduction Connecting the DC buses of frequency converters together results in energy savings and in some cases simplifies the connection to the main supply. With common DC the braking energy of one converter can be used for the other converters and motors.
Possible main supply connections Figure 1. Common DC connections. Cases a and b. R7 / R6 R7 / R5 Figure 2. Common DC connections. Cases c, d1 and d2. Cases b, c and d can be used when the total power taken from the main supply, , is smaller than the drive power rating, P , of the biggest converter.
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Note: With ACS800-11 only connection presented in case d1/d2 is allowed. Note: With ACS800-11 220 V units, the voltage drop over the charging resistor during charging can generate a permanent undervoltage fault. Contact your local...
Step by step guide 1) Select the converters and preselect the main supply connection. See Possible main supply connections Appendix A Charging circuit capacity. 2) Check from Table 1 that the connection is possible. 3) Check by using equation 1 that the load does not exceed the total power limit of the system.
The power correction factor, k, for each combination can be found from Table 1. When several converters are connected to the main supply, the least efficient power correction factor is chosen from table 1, i.e. the smallest factor. See Example1 Example2. Table 1 Power correction factors ACS800 R2-R3 R5-R6 R7-R8 R2-R3 k=0.5 k=0.7...
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Example1 The DC buses of three converters ACS800-0004-5, 2.2 kW, R2; ACS800-0025-5, 18.5 kW, R3 and ACS800-0025-5, 18.5 kW, R3 are connected together. The input terminals of the 2.2 kW converter are left unconnected. According to Table 1, k = 0.5 when two R3´s are connected to the main supply, therefore P...
Because of the complicated fault current paths the selectivity of the fuses cannot be guaranteed in all conditions. aR fuses must be installed on both DC wires. Table 2 Recommended DC side aR fuses. ACS800-01/04/11 Frame size 230 V 400 V...
Cables • Select the input power cables as described in the appropriate drive Hardware Manual. The cross-sectional area of the DC cables must be the same as the cross-sectional area of the AC side cables. • If screened DC cables are used, ground the screen at the other end only. •...
Allowed braking power and need for a brake resistor 1. For each drive check that the braking power does not exceed the allowed braking power. See Calculation of the allowed braking power below. 2. For the common DC system check whether it needs to be equipped with an additional brake chopper and resistor.
Calculation of the allowed braking power If drive is not connected to the main supply, ensure that the braking power meets condition 1 below. If drive is connected to the main supply, ensure the braking power meets condition 1 AND condition 2 below. Condition 1 The drive braking power may not exceed the drive power rating.
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The DC buses of three converters ACS800-0140-5, 110 kW, R6; ACS800-0140-5, 110 kW, R6, and ACS800-0070-5, 55 kW, R5 are connected together. Only one 110 kW converter is connected to the main supply. The duty cycle is shown in the table below.
Internal brake chopper • Only one internal brake chopper is allowed to be active. • If an internal chopper is used, it must be in the biggest converter. • The maximum braking power of the brake chopper or the inverter must not be exceeded.
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Peak current through the contactor in brake resistor circuit can be calculated with equation 5. ⋅ 1.21 U I ˆ ------------------------- (equation 5) brake The rms current during the braking can be calculated with equation 6. (equation 6) ------------- brake is the brake resistor‘s resistance.
Wiring Supply Use the same supply connection point. All converters must be fed from the same transformer. The supply impedance is an important parameter, which influences the current distribution. All converters must have equal supply impedance. Powering the AC fans in R7 and R8 Appendix B Powering the AC fans of R7 and R8 for more information.
Phase loss guard It is recommended to use phase loss guard in the input supplies of all of the converters. If phase loss guard is not used and the fuse of one of the input supply phases blows, the semiconductors of the converters may be overloaded and damaged.
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Figure 4. READY signal wiring example. Wiring...
Always check the setting of parameter 16.15 I/O START MODE after software update, macro change or control board replacement! See ACS800-11 Hardware Manual for information on how to change the line-side converter parameters with control panel. Start-up...
Appendix A Charging circuit capacity The total power of the common DC system P is higher if the smallest converter out.tot is not connected directly to the main supply. To determine whether it is possible to leave some converters unconnected, the total charging energy of the DC capacitors and associated inrush currents must be analysed.
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5700uF 10800uF 1.35 500V 4829J Even if the charging resistor of the ACS800-0260-5 (R7) is able to withstand the whole charging energy, E = 4829 J < E = 5600 J, the biggest converter ACS800-0400-5 (R8) is connected to the main supply.
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Example 6 The DC buses of two ACS800-0120-5 (R6) and four ACS800-0260-5 (R7) are connected together. The main supply voltage is 500 V. The total charging energy of the DC link capacitors is 6 – ⋅ ⋅ ⋅ ⋅ ⋅...
Appendix B Powering the AC fans of R7 and R8 If the supply of frame size R7 or R8 is not connected to the main supply, the AC fan must be powered separately. Feed the primary of the fan circuit transformer with the converter’s nominal main supply voltage, V- and W-phases, via the built-in fan circuit.
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ABB Oy ABB Inc. AC Drives Automation Technologies P.O. Box 184 Drives & Motors FI-00381 HELSINKI 16250 West Glendale Drive FINLAND New Berlin, WI 53151 Telephone +358 10 22 11 Telefax +358 10 22 22681 Telephone 262 785-3200 Internet http://www.abb.com...