Liebert NX UPS System user manual Power Cables, Maximum steady state AC and DC currents

Single Module UPS Installation

1.6Power Cables

The cable design must comply with the voltages and currents provided in this section, follow local wir- ing practices and take into consideration the environmental conditions (temperature and physical support media).

For cable entry terminal, refer to Figure 22.

! WARNING

Before starting the UPS, ensure that you are aware of the location and operation of the external isolators that connect the ups input/bypass supply to the mains distribution panel.

Check that these supplies are electrically isolated and post any necessary warning signs to prevent their inadvertent operation.

! WARNING

Failure to follow adequate earthing procedures may result in electromagnetic interference or in hazards involving electric shock and fire.

Table 1	Maximum steady state AC and DC currents
				Nominal Current, Amps						Busbar Stud Size
	Input Mains Current 1,2				Output Current2				Input/Output/
	With Full Battery
		Recharge			at Full Load				Bypass
			3ph + N			3ph + N			Cables		External
UPS								Battery at		Hole	battery	Torque
Rating								End of		Dia.	Cables	Load
(kVA)	380V		400V	415V	380V	400V	415V	Discharge	Bolt	(mm)	(Bolts)	(Nm)
10	22		21	20	15	14	13	22
15	33		32	31	22	21	20	33	M6	6	M6	5
20	44		43	42	30	29	28	44
30	63		62	61	45	44	42	66

1.Input mains current listed for common rectifier and bypass AC input. For split input the rectifier current is 94% of the currents listed.

2.Non-linear loads (switch mode power supplies) affect the design of the output and bypass neutral cables. The current circulating in the neutral cable may exceed the nominal phase current. A typical value is 1.5 In.

3.Protective earth cable: Connect each cabinet to the main ground system must follow the most direct route possible.

The earth conductor shall be sized in accordance with the AC supply fault rating, cable lengths and type of protection. Typical cross sectional areas are 2.5mm2 (10kVA), 6mm2 (15kVA), 10mm2 (20kVA), 16mm2 (30kVA), as per AS / IEC 60950-1

4.When sizing battery cables, a maximum volt drop of 4 VDC is permissible at the current ratings given in Table 1. The load equipment is generally connected to a distribution board containing individually protected busbars rather than connected directly to the UPS output. The output cables from paralleled units to the parallel distribution bus should be of same length so as to optimise the sharing of current. Do not form coils, so as to minimise the formation of electromagnetic interference.

5.For terminal location – refer to 4.0 - Installation Drawings)

Table 2 Distance from floor to connection point on the equipment

	Minimum Distance
UPS	mm (in.)
Rectifier A.C. Input supply	284 (11-1/5)
Bypass A.C. Input supply	284 (11-1/5)
UPS Output A.C.	369 (14-1/2)
Battery Power	369 (14-1/2)
Auxiliary cables: Monitor board (U2)	1104 (43-1/2)

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