APC 20 - 200 KVA user manual Redundant, parallel UPS, Start-up

Maintenance (cont.)

Redundant, parallel UPS

See figures 27 and 28 in the Appendix. During maintenance, a UPS unit must be isolated from the normal AC source, its battery and the output circuits of the other UPS units.

◗isolate one UPS (see figure 27) Proceed in the following order (see figure 25 without Q3BP):

◗shut down the inverter (press the "inverter OFF" button 9 for three seconds),

◗open isolating switches Q5N, Q4S, QF1 and Q1.

The UPS unit is powered down once the capacitors have discharged (a few minutes);

◗start-up

Following servicing, proceed in the following order (see figure 26 without Q3BP):

◗close switch Q1, then after approximately ten seconds, switches QF1, Q5N and Q4S,

◗start the inverter (press the "inverter ON" button 8 ).

Note: if the load is still supplied

by an inverter, the Q3BP switch on the unit undergoing maintenance must not be closed.

To fully isolate the installation, proceed as indicated below:

◗isolate all UPSs (see figure 28) Proceed in the following order (see figure 25):

◗shut down the inverters (press the "inverter OFF" buttons 9 for three seconds),

◗close the Q3BP switches used to bypass the units (no units have priority),

◗open isolating switches Q5N, Q4S, QF1 and Q1.

The UPS units are powered down once the capacitors have discharged (a few minutes).

◗start-up

Following servicing, proceed in the following order (see figure 26):

◗close switches Q1, then after approximately ten seconds, switches QF1, Q5N and Q4S,

◗open the Q3BP switches,

◗start the inverters (press the "inverter ON" buttons 8 ).

Q1	A	B
		Q5N
1
	QF1
	D
2	Q4S
	Q3BP	C
Q1	A	B
		Q5N
1
	QF1
	D
2	Q4S
	Q3BP	C

Fig. 27

Q1	A	B
		Q5N
1
	QF1
	D
2	Q4
	Q3BP	C
Q1	A	B
		Q5N
1
	QF1
	D
2	Q4S
	Q3BP	C

Fig. 28

E-51028230XT/BG - 35