UPS Systems Flashcards
Describe the basic function of an uninterruptible power supply to include:
Internal Components – UPS Battery, Rectifier, Inverter, Static Switch
Theory of Operation – A backup power source that provides uninterrupted power to a load after main power fails. Also creates clean, AC power.
Rectifier: Converts AC to DC to charge batteries.
Battery: Outputs stored power for emergency use.
Inverter: Converts DC power to AC for use by customer load
Static (Bypass) Switch: Allows incoming AC power to bypass rectifier, batteries, and inverter.
Sequence of Operation – Rectifier converts AC to DC, charges battery, inverter converts DC back to AC, and supplies load down the line.
Alarming Setpoints – Abnormal noise, hi/lo current and voltage, over temp (>77) for batteries, fan failure, inverter/rectifier failure, comms failure
Maintenance Scope of Work
Check voltages, inspect connections, AC/DC capacitors, clean/replace air filters, firmware upgrade, UPS annual pm and daily inspection, batter annual and quarterly pm.
APC
L1 (excluding 200F)
VRLA (435/32=13.5V) /Li-Ion (435/13=33.3V)
Galaxy
L2
Li-Ion (572/17=33.6V)
Vertiv Liebert
L200F and House UPS
VRLA (540/40=13.5V)
Describe the general procedure for placing the UPS system into maintenance bypass and the reasoning behind performing each step.
Contact OPS center that work will begin
“Start work” in Insite
Verify no alarms
Note KW reading at critical bus panel meter and make sure the UPS doesn’t exceed 75% of its rated capacity
40 CAL suit
At breaker UPX-MBB, pump charging handle repeatedly to compress spring and charge the breaker
Touch “initiate transfer” button on UPS graphic screen to transfer from online to static bypass
Note KW reading at critical bus panel meter
At UPS SKRU (Solenoid Key Release Unit) verify release button is illuminated
Depress release button and rotate key 180 degrees to release key
Remove key
At UPS-MBB inset key into lock cylinder
Rotate key 90 degrees to unlock breaker
Close breaker UPS-MBB
Verify breaker flag indicates closed
Note KW reading at critical bus panel meter
At breaker UPX-MIB pump charging handle to charge breaker
Open breaker UPX-MIB
At UPX-MIB rotate key to lock
Remove key from cylinder
At UPX SKRU verify release button is not illuminated
Insert key
Rotate 180 degrees to capture key
Note KW reading at critical bus panel meter
What might be a reason the UPS would be on static?
An in-rush current
Where are the Vertiv UPS’s?
L200F, Room 173, and Room 199
What does DR stand for?
Distributive Redundancy
Describe the electrical systems in detail including:
Distributed Redundant electrical distribution – N+2
PLC timing set points
Utility Return – 30 mins
Utility Fail Reset – 3 secs
Sync Fail Preset – 2 min
Gen Fail Preset – 18 secs
Open Transfer Delay Preset – 1 sec
Closed Transfer Delay Preset – 1 sec
The difference between open and closed transfer
Open – Break before make
Closed – Make before break
The difference between active and passive transfer synchronization
Active – gen seeks to match utility
Passive – gen waits for natural sync
PLC failure reset procedure for Siemens
Service – Exit Runtime (Restart) – Exit App and Restart
Follow EOP
Describe the general operation of an Automatic Transfer Switch including:
System differences between ASCO, Kohler, and Bodine
ATS continuously monitors electrical power, senses power issues and transfers power, once power is restored, switches back.
ASCO: Electric Rooms
Kohler: MAU’s
Bodine: Pre-actions and dampers
The differences between the different systems has to do with voltage and amperage
Vista switch, what is it and what does it do?
It is an underground distribution switchgear that seeks the best power source between the sub stations.
Describe the general operation of a Lighting Control Panel
Timer and Schedule
Describe the general function of the TVSS (Transient Voltage Surge Suppressor)/SPD (Surge Protection Device)
To protect equipment from power surges, diverts excess voltage and current ground. Allow low current to flow to equipment as required.
Acts as cut off in case of momentary spike/surge of electric power.
Describe the purpose of a multifunctional relay
Sel 751: is a multifunctional relay used for automation and control. It monitors utility/generator voltage, current and frequency to look for sags, swells and losses. If any of the conditions go out of range for a pre-set amount of time, it will tell the PLC. The PLC then tells the utility/generator breakers to open or close when appropriate. It uses a 24vDC control circuit to control the 480vAC breakers. It also gives us the ability to manually manipulate the breakers if the PLC were to fail. They give us a 5 second interval between pressing CLOSE/OPEN on the SEL to when the breaker event occurs for safety.
Over/Under Voltage, Frequency; Looks for Sags, Swells, Losses. Then communicates with PLC
Where do the IDF rooms feed from?
L100
