Okay, M, this is a tough situation but we can break it down. It sounds like you've done a good job documenting everything. Here's a troubleshooting approach, focusing on safety and systematic problem-solving, considering your limitations as a building engineer

Key Principles:
Safety First

High voltage is dangerous. Do NOT attempt to work on the switchgear yourself. This requires qualified, licensed electricians with experience in medium voltage systems. Your role is to provide clear information to them.

Document Everything

Keep a detailed log of everything you do, observe, and every test result.

Isolate, Test, then Restore

This is the fundamental principle. Isolate the problem area, test it thoroughly, and only restore power once you are certain it is safe.

Don't Assume

Even if something seems obvious, verify it.

Troubleshooting Steps


Gather Information for the Electricians



Breaker Type

Get the manufacturer and model number of the 1600A breaker. This is crucial for understanding its protection settings.

Trip Unit Settings

Carefully record all settings on the breaker's trip unit (the protection module). Note the settings for: Long Time Pickup (Amps) Long Time Delay (Time) Short Time Pickup (Amps) Short Time Delay (Time) Instantaneous Pickup (Amps) Ground Fault Pickup (Amps) Ground Fault Delay (Time) Is there a specific curve setting for any of these functions (like an I2t curve)?

Protective Relays

Check if there are any separate protective relays associated with the 1600A breaker. If so, note their manufacturer, model, and settings.

Shunt Trip/Undervoltage Release

Determine if the breaker has a shunt trip or undervoltage release, and how they are configured.2.

Consult with Qualified Electricians



Experience is Key

Find electricians who specialize in medium voltage switchgear and have experience with the specific type of breaker installed.

Share Information

Provide them with all the information you gathered in Step 1, along with a detailed description of the events, the hurricane damage, and the replacement of the feeder cables.

Review Existing Settings

Have the electricians review the trip unit settings to ensure they are appropriate for the load and coordination with upstream/downstream protective devices. Incorrect settings can cause nuisance tripping.3.

Systematic Load Testing

(This is where the electricians will be heavily involved)

Verify Isolation

Double-check that the garage lighting (HG1/HG2) is completely isolated at the fused disconnects. Physically disconnect the load side conductors at the disconnects, if possible, for complete certainty.

Chiller 2 Testing



Megger Testing

Have the electricians perform a megger (insulation resistance) test on the chiller 2 motor windings before attempting to start it. This will check for insulation damage.

Gradual Loading

If the megger test passes, have the electricians monitor the current draw on each phase as chiller 2 starts up. A sudden spike in current, or an imbalance between phases, could indicate a problem.

Monitor Voltage and Frequency

Observe the voltage and frequency at the switchgear as chiller 2 loads up. Low voltage or unstable frequency can cause overcurrent conditions.

Isolate Other Loads

If chiller 2 is causing the tripping, try isolating the other loads on the 1600A breaker (ATS, garage elevators, pump motors/cooling tower drives) one at a time to see if any of them contribute to the problem.4.

Ground Fault Investigation



Ground Fault Location

The electricians should use ground fault tracing equipment to try to pinpoint the location of the ground fault. This may involve disconnecting loads one at a time and checking for ground faults on each circuit.

Neutral-Ground Bonding

Verify that the neutral-ground bonding is correct at the switchgear and at any downstream transformers or subpanels. Improper bonding can cause circulating ground currents.5.

Breaker Testing and Inspection



Full Breaker Testing

Even though the breaker was refurbished, it should be thoroughly tested under simulated fault conditions.

Internal Inspection

Have the electricians inspect the internal components of the breaker for signs of damage, corrosion, or contamination from the saltwater.6.

Shunt Trip/Undervoltage Release Troubleshooting



Shunt Trip

If the breaker has a shunt trip, the electricians should check the wiring to the shunt trip coil for shorts or grounds. They should also verify that the shunt trip circuit is not being inadvertently activated by any other equipment.

Undervoltage Release

Similarly, if the breaker has an undervoltage release, the electricians should check the voltage to the undervoltage release coil to ensure it is within the proper range. Low voltage to the coil can cause the breaker to trip.

Possible Causes and Considerations



Insulation Damage

Saltwater is extremely corrosive and can damage insulation on conductors and equipment, leading to ground faults or phase-to-phase faults. Even with the feeder cables replaced, there may be damage to equipment connected to the 1600A breaker.

Loose Connections

Corrosion can also cause loose connections, which can lead to overheating and voltage drops.

Ground Fault Sensitivity

The ground fault settings on the breaker may be too sensitive, causing it to trip unnecessarily. However, before increasing the ground fault settings, it's important to rule out any actual ground faults.

Harmonic Distortion

Harmonic distortion from non-linear loads (like variable frequency drives used for the chiller plant pumps and cooling tower drives) can cause the breaker to trip. The electricians should use a power quality analyzer to check for harmonic distortion.

Motor Starting Inrush

The inrush current when starting large motors (like the chiller 2 motor) can sometimes cause breakers to trip, especially if the breaker is not sized properly.

Your Role in the Process



Clear Communication

Maintain open and clear communication with the electricians. Provide them with all the information they need and ask questions to understand what they are doing and why.

Follow Instructions

Follow the electricians' instructions carefully. Do not attempt to work on the switchgear yourself unless you are qualified and authorized to do so.*

Documentation: Continue to document everything that is done, including test results, changes to settings, and any repairs that are made.By following these steps and working closely with qualified electricians, you should be able to identify and resolve the problem with the 1600A breaker. Good luck! Remember, safety is paramount. Flag for review