Okay, let's break down how to get you the information you need and potentially get the attention of someone knowledgeable.1. Finding the Schematic



ASCO Documentation

This is always the first and best bet. ASCO (now owned by Schneider Electric) maintains a support website. Even for older models, they sometimes have archived documentation. Here's how to search: Go to the Schneider Electric website (the parent company of ASCO). Search for "ASCO 940 transfer switch manual" or "ASCO 940 transfer switch schematic". Look specifically for results that include documentation from the 1990s or early 2000s. Check the results for documents that cover "engine controls," "optional switch," or "time delay relays."

Online Forums and Communities

Beyond Electrical Engineering Stack Exchange, try other forums dedicated to: Backup generators Automatic transfer switches Power systems Industrial maintenance

Commercial Schematic Databases

Some companies specialize in archiving and providing access to schematics for industrial equipment. These often require a subscription or per-document fee. Examples include: IHS Markit (now part of S&P Global) GlobalSpec

Local Electrical Supply Houses

The electrical supply house that originally sold the ASCO switch might have records or contacts that could help you find the schematic. If you know where the switch was purchased, it's worth a try.

Generator Service Companies

Companies that specialize in servicing and maintaining generators often have libraries of schematics for various ATS models. They might be willing to share information (for a fee, potentially).

2. Gathering More Information On-Site

When you return to the site, focus on these details:

Exact ASCO 940 Model Number

Look for a nameplate on the ASCO 940 transfer switch. Get the complete model number. This is critical.

Detailed Photos

The entire control panel. Close-ups of the optional "SS" switch, showing its markings and wiring. The time delay relays ("TR" and/or "TD"), including their model numbers and wiring. All terminal blocks and wiring connections related to the engine controls. Any other labels or markings on the control panel.

Wiring Diagram (if present)

Sometimes, a simplified wiring diagram is pasted inside the enclosure. Take clear photos of it.

Component Markings

Note the part numbers and manufacturers of any relays, timers, or other components in the control circuit.

Trace the Wiring

Carefully trace the wiring from the "SS" switch and the time delay relays. Note where the wires connect to other components. This will help you understand the circuit's function.

3. Understanding the Operation (Based on Your Description)

The "SS" switch is clearly intended to override the automatic operation of the generator. Here's a likely scenario:

OFF

The generator is completely disabled from starting, regardless of power outages.

AUTO

The generator starts automatically when normal power fails.

MANUAL ON

The generator is forced to start, regardless of whether normal power is available. This is typically used for testing.The problem you're describing suggests that the "AUTO" position is incorrectly triggering the generator start even when normal power is present.

4. Troubleshooting Steps (Without a Schematic)



Check the "SS" Switch

Use a multimeter to verify that the "SS" switch is functioning correctly. In the "AUTO" position, it should not be making a connection that initiates the generator start signal when normal power is available. The problem could be a faulty switch.

Inspect the Time Delay Relays

These relays are likely used to provide a delay before starting the generator after a power outage or to allow the generator to run for a short period after power is restored. Check their wiring and settings. A faulty time delay relay could be causing the generator to start prematurely. If you can find the model numbers, look up the datasheet for each relay to understand its operation.

Look for Common Issues

Check for loose wiring, corroded connections, and damaged components.

Verify Voltage Levels

Use a multimeter to check the voltage levels at various points in the control circuit. This can help you identify where the fault is occurring.

Safety First

Be extremely careful when working with electrical equipment. Always disconnect the power before working on the control panel.

5. "Pinging" Someone (Regarding User Mentions)

Yes, typing `@ATSman` should notify the user ATSman if they have their notification settings enabled. Whether or not they will respond depends on their availability and knowledge of the specific switch in question.

Important Considerations



Safety

Working on electrical equipment is dangerous. If you are not qualified and comfortable working on electrical systems, hire a qualified electrician.

Documentation

Always document your work, including photos and notes. This will help you troubleshoot problems in the future.

Modification: Avoid making any modifications to the wiring or control circuit without a schematic and a thorough understanding of the system.Good luck! Providing the exact model number of the ASCO 940 will greatly increase your chances of finding the correct schematic. Flag for review