Energy Tech Laboratories EDP70 manual MI00/10056 rev.1--05/2001

Reserve Supply

AC Supply

S3 Maintenance By-pass

S2
S1	S4
Battery	24/36kVA Ratings
Contactor

S3 Maintenance By-pass

Reserve Supply	S2	S5
	S1	S4
AC Supply
	Battery	50/80kVA Ratings
	Contactor

480Y/277V

208Y/120V

Figure 5 – Re-establishing the Utility Supply

When the utility supply returns within acceptable limits, the UPS returns automatically to normal operation mode as previously described. The rectifier now starts to recharge the battery. However, until recharge has been completed, any further mains failure will result in reduced standby times.

S3

Reserve Supply S2

S1

AC Supply

S3

Reserve Supply S2

S1

AC Supply

Maintenance By-pass

S4

Battery

Contactor 24/36kVA Ratings

	Maintenance By-pass
	S5
	480Y/277V
	S4
	208Y/120V
Battery	50/80kVA Ratings
Contactor

Figure 6 – Transferring the Load onto the Reserve Supply

Transfer onto the reserve line is caused by two conditions:

a)inverter stop

b)overload

In both instances the load is transferred onto the reserve without interruption. If the overload is temporary, the system will re-transfer from reserve to inverter as soon as the it ceases. This allows for the initial start-up of loads with high or excessive switch-on currents.

page 10 --MI00/10056 rev.1--05/2001