UPS Electrical Function Test and Field Inspection.

Field inspection and electrical testing of an Uninterruptible Power Supply (UPS) are critical processes to ensure its reliability, safety, and operational efficiency. These inspections and tests verify that the UPS is in good working condition and can provide uninterrupted power to your critical systems during power outages or fluctuations.

Here’s a general guide on how these inspections and tests can be conducted:

Visual and Mechanical Inspection.

UPS Mechanical Inspection Checklist.	Yes	No
1. All components have been checked against one-line diagram and have been signed off by all departments.
2. Safety equipment in place and serviceable as per standards.
3. All power and control wiring tested, marked, color coded and properly phased (AC/DC circuits).
4. HVAC checked out, operational and on.
5. All cabinets, enclosures and rooms clean.
6. Replacement power and control fuses, control boards available for both inverter and rectifier.
7. Normal power is available for start-up and commissioning.
8. All vendor (manufacturer) manuals and factory test documents are available.
9. Batteries tested per Manufacturers instructions.

Electrical Inspection Checklist.

Inspection Checklist	Yes	No
1. UPS start-up procedure approved and available.
2. Verify inverter check-out by vendor Representative.
3. Witness and verify output wave forms are correct.
4. Witness and verify output voltage is set and correct.
5. Witness and verify all alarm functions.
6. Witness and verify static switch function.
7. Verify operation of manual bypass switch.
8. Verify all voltmeters/ammeters are calibrated and correct.
9. Insure Operations has sufficient operator training on UPS system.

Electrical Function Testing.

Equipment Required:

1. Digital Voltmeter (DVM).
2. Spectrum Analyzer to 10 Khz.
3. Multi-amp tester.
4. Dual trace Oscilloscope, (ungrounded plug).

1. UPS on line and Unloaded.

	Yes	No
a. Connect Oscilloscope and DVM to UPS output, compare reading to the installed output meter.
b. Take Polaroid photo or draw wave form and compare wave form of output to vendor illustration.
c. Make adjustments per vendor instruction manual if required.

2. UPS on line and Loaded.

	Yes	No
a. Repeat steps a, b, and c in (1) above.
b. Switch “off” Primary feed, monitor Oscilloscope for switching transients, voltage level, and wave from purity. Make adjustments per static switch vendor instruction manual if required.
c. Reinitialize UPS inverter per vendor manual, check synchronization indicator and time to synchronize
d. Perform vendor under voltage and over-current switching checks, using multi-amp test set. Monitor the UPS output with DVM and Oscilloscope. Adjust if necessary.
e. Connect Spectrum Analyzer to UPS output. Set to 7th harmonic and log vertical scale. Calculate the amplitude of each harmonic. If harmonic amplitudes exceed 4% corrections must be made.
f. Remove Primary and Alternate power supplies and monitor UPS output. Repower the system with Primary and Alternate power supplies when the output amplitude starts decreasing.

General UPS Electrical Testing.

1. Battery Tests:
   • Voltage Test: Measure the voltage of the battery or battery strings to ensure they are within the manufacturer’s recommended range.
   • Load Test: This involves applying a load to the battery to simulate real operating conditions. It helps in assessing the battery’s ability to hold a charge and deliver power when needed.
   • Resistance Test: Checking the internal resistance of the battery can help identify if any cells are weak or failing.
2. Input and Output Test:
   • Voltage and Frequency: Check the input and output voltage and frequency with the UPS running in normal and battery modes. Ensure they match the specified parameters.
   • Transfer Time: Measure the transfer time from mains to battery and vice versa. This should be within the limits specified by the manufacturer.
3. Functionality Test:
   • Bypass Operation: Test the manual and automatic bypass operations to ensure the UPS can transfer the load to mains power without interruption.
   • Alarm and Indicators Test: Verify that all alarms and indicator lights function as intended for various fault conditions.
4. Load Test:
   • Perform a load test by connecting a load equivalent to what the UPS would typically support. Check for any issues in supplying power under normal and battery modes.
5. Calibration:
   • Some UPS systems require calibration of certain parameters. Follow the manufacturer’s guidelines to perform these calibrations if necessary.

Safety Precautions.

• Always follow the manufacturer’s safety instructions and wear appropriate personal protective equipment (PPE).
• Ensure the UPS is disconnected from any external power source before performing internal inspections or maintenance, if required by the procedures.
• Be aware of the risks involved in handling batteries, including chemical and electrical hazards.