Mike Dolt Enterprises
Mike Dolt Enterprises
User: sfav8r, Location: San Francisco Bay Area
Asked on: Wednesday, June 1, 2011 at 12:00 pm EDT
Answered on: Tuesday, May 14, 2024 at 6:05 am EDT
Question: I have been asked to help a client with a problem that started with the installation of a new elevator. After the installation of the new elevator, the emergency transfer fails. When this was first discovered, they were told by the elevator company that their generator was too old to handle the new elevator equipment and that a new generator would have to be installed. I believe the assumption at that time was that it was a phasing problem and the old generator/regulator could not respond fast enough. Now, one of the people involved says that the problem is the transfer switch and that the switch should be changed or a delay should be installed in the ATS.This is an area I have very little experience in. However, I have worked with the client for a long time and they trust me to help them get to the bottom of this since different people are telling them different things. I am setting up a meeting with the elevator company and the generator company to do some fact finding and would appreciate any input from anyone with experience doing this.The plan at this point is to determine the following:1) What EXACTLY is the failure? Does the generator shut down or does the transfer work correctly but the elevator shuts down?2) What does the elevator company mean specifically when they say a delay is needed?3)What are the requirements of the elevator in terms of phase accuracy/power qulity? - What are the capabilities of the generator?One thing that is puzzling me is that to be compliant with the local codes, they currently have a mobile genset connected. If the transfer switch is the problem, what good is the mobile genset? It would be using the same ATS.What question would you want answered? I just need to help them determine what the real problem is and then find someone with a strong background in this area to complete the work. I would be happy to pay a consulting fee to someone sharp in this area. If that's you, feel free to PM me. Also, if someone knows someone in the SF Bay Area that knows this stuff in their sleep, it may be an opportunity to do the repair/installation.Thanks
Questions to Answer
Check for Test Switch
Ensure that there is no test switch or bypass that may be causing the failure.
Verify Generator Output
Confirm that the generator is actually providing power. Check voltage, frequency, and harmonics.
Evaluate Transfer Switch Contacts
Inspect the transfer switch contacts for any burn marks, loose connections, or arcing that could indicate a problem.
Check for Synchronization Issues
Determine if there is a mismatch between the phase and frequency of the generator output and the utility power.
Test Elevator's Response
Simulate a power outage and observe the elevator's behavior. Does it shut down immediately or does it continue to operate with the generator power?
Assess Generator Capacity
Determine the power requirements of the elevator equipment and ensure that the generator is capable of handling the load.
Inspect Interlock Wiring
Verify that the interlock wiring between the elevator, generator, and transfer switch is correct and functioning properly.
Regarding the Delay
Surge Current
Elevators often draw a large surge current when starting, which can lead to a voltage dip. A delay in the ATS allows the generator to stabilize before the elevator starts, minimizing the voltage dip.
Generator Protection
A delay can also protect the generator from damage caused by excessive surge currents.
Elevator Requirements
Phase Accuracy
The elevator may require a specific phase sequence or voltage tolerance for proper operation. Determine these requirements from the elevator manufacturer.
Power Quality
The elevator may also have specific requirements for power quality, such as limits on voltage fluctuations and harmonics.
Mobile Genset
Transfer Switch Type
The mobile genset may be using a different type of transfer switch that is not affected by the same problem.
Interlock Bypass
Check if the mobile genset has a bypass switch that allows it to bypass the ATS and connect directly to the elevator.
Consultant/Contractor Considerations: Look for a consultant or contractor with experience in elevator emergency transfers and generator synchronization. Ensure they have a strong understanding of power quality and electrical code requirements. Request references and ask about their specific experience with similar projects. Flag for review