Multi-Module System Without External Output Circuit Breaker 1 - Emerson Liebert NX 400V User Manual

output becomes enabled but interlocking works now.
10. Turn On inverter and join the parallel system.
7.7.2

Multi-Module System Without External Output Circuit Breaker 1

This procedure is indicated for isolation of one UPS module from other modules of a group of other-
wise normally operating paralleled UPS modules. Only the power switches, isolators and circuit
breakers in the module to be isolated will be opened. This procedure does not require the supply of
any bypass power to the critical load.
1. Turn Off the inverter
2. Open Internal Output isolator (Q5) but keep Internal Maintenance Circuit Breaker open.
The UPS enters Isolation Status automatically, parallel signaling and communication become
masked, and internal output becomes inhibited.
3. Power Off unit for maintenance.
4. Power On unit with Internal Output isolator (Q5) open.
5. The UPS enters Test Mode by configuration software setting.
6. Diagonosis or testing.
7. The UPS exits Test Mode by configuration software setting.
Output becomes inhibited because of Isolation Status.
8. Return all switches of Unit 1 to the Normal position, including Internal Output Circuit Breaker 1.
When Internal Output isolator (Q5) is closed, unit will exit Isolation Status automatically, parallel
signaling and communication recovers, output becomes enabled but interlocking works now.
9. Turn On Inverter1 and join the parallel system.
WARNING
!
Hazardous Battery Voltage
No operator serviceable parts are located behind covers that require a tool for their removal.
Only qualified service personnel are authorised to remove such covers.
The UPS battery and connecting terminals remains energized at hazardous voltage levels at
all times. The battery is located behind protective covers that require a tool for their removal:
inside the UPS cabinet (30 and 40kVA models), inside a free-standing battery cabinet or on
open racks inside a dedicated battery room that may be locked.
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Operating Procedures