Okay, testing an ATS without connecting the generator is a good practice. Here’s a breakdown of how to approach this, focusing on safety and avoiding damage to the ATS or the utility power system.

Important Safety Precautions



Lockout/Tagout (LOTO)

Absolutely essential! Before doing anything, ensure both the utility power feed to the ATS and any potential power feed from the generator side (even if the generator isn't connected, circuits might be wired) are properly locked out and tagged. This prevents accidental energization during testing.

Verify absence of voltage with a meter. This cannot be skipped. Qualified Personnel

This work should be performed by qualified electricians or technicians who understand electrical safety procedures and ATS operation.

Read the Manuals

Consult the ASCO 7000 ATS manual and the Cummins generator manual (even though the generator isn’t connected yet) for specific instructions, wiring diagrams, and potential troubleshooting steps. The manuals are your primary resource.

Personal Protective Equipment (PPE)

Wear appropriate PPE, including safety glasses, gloves, and any other required safety equipment.

Double-Check

Before applying any simulated signals or manipulating switches, double-check all connections and settings. Incorrect wiring or settings can damage the ATS.

Testing Steps (Simulating Generator Failure and Restoration)

Here's a logical sequence:1.

Visual Inspection

Carefully inspect the ATS for any signs of damage, loose connections, or corrosion. Verify that all wiring connections are tight and secure. Check that all control switches and indicator lights are in their normal positions.2.

Voltage Monitoring (With Power Restored AFTER LOTO Removal and Verification)

Carefully restore utility power to the ATS (AFTER removing the LOTO and verifying the absence of voltage from the generator side). Monitor the voltage levels on both the utility and generator sides of the ATS using a multimeter. Verify that the voltage is within the specified range for the ATS. Document these baseline voltage readings.3.

Simulating a Utility Power Failure

This is the core of the testing process. There are several ways to simulate a power failure, choose the one that's safest and most appropriate for your setup:

Preferred Method: Control Wiring Simulation (Safest and Most Controlled)



Identify the Under-Voltage (UV) Relays or Control Terminals

The ASCO 7000 uses undervoltage relays to detect a loss of utility power. Refer to the ATS wiring diagram to locate these relays (typically labeled UV1, UV2, UV3 per phase, or similar). The goal is to safely simulate the UV relays dropping out.

Isolate and Test

Instead of disconnecting main power, you can often safely simulate a UV condition by disconnecting or shunting the control wiring to the UV relays.

Crucially, DO NOT disconnect the main power wires feeding the ATS. This requires understanding the control circuit. For example, if the UV relays are powered by a control transformer, you could temporarily disconnect (or short, if designed that way) the control power to the UV relays only. Monitor Response

When the UV relays simulate a power failure, the ATS should initiate its transfer sequence. Monitor the indicator lights on the control panel to verify that the ATS is responding correctly. You should see the "Utility Source Unavailable" light illuminate (or similar).

Return to Normal

Once you've confirmed the response, restore the control wiring to the UV relays. The ATS should return to its normal state.

Less Preferred (and potentially more risky) Method: Controlled Voltage Reduction (Use ONLY if absolutely necessary and with EXTREME caution)



Using a Variable Transformer (Variac)

You can slowly and carefully reduce the voltage on one or more phases of the utility input using a Variac. This simulates a brownout or complete power loss.

This method requires extreme care to avoid damaging the ATS or creating a real power outage. Monitor Carefully

Constantly monitor the voltage levels and the ATS response. As the voltage drops, the ATS should initiate the transfer sequence.

Do NOT Overdo It

Only reduce the voltage to the point where the ATS initiates the transfer. Do not drop the voltage to zero suddenly.

Restore Voltage

Slowly increase the voltage back to normal to simulate power restoration.4.

ATS Transfer Mechanism



Observe the Transfer

During the simulated power failure, observe the ATS transfer mechanism (the contactor or circuit breaker that switches the load). You should hear and/or see it operate.

Timing

Note the time it takes for the ATS to transfer the load after the simulated power failure. Compare this to the specified transfer time in the ATS manual.

Return to Source

When you "restore" utility power (either by reconnecting the UV relay control wiring or raising the voltage), the ATS should automatically transfer the load back to the utility source after a pre-set time delay (if configured that way). Observe the transfer and note the timing.5.

Simulating Generator Availability (Dry Contact Closure)



Locate Generator Start Signal

Identify the terminals on the ATS that are intended to receive the "generator available" or "generator running" signal from the generator control panel (often a dry contact closure). The ATS wiring diagram is essential here.

Simulate Generator Running

Use a jumper wire to momentarily simulate the closure of the generator available contact. This should signal to the ATS that the generator is ready to accept the load.

Do not leave the jumper in place for an extended time Observe Response

Monitor the ATS. It might have indicator lights or a screen that shows the generator status. The ATS should not transfer the load to the "generator" side because there's no actual generator connected. The purpose of this test is to confirm the ATS recognizes the generator available signal.6.

Time Delays and Setpoints



Verify Settings

Check the ATS settings for various time delays, such as: Time delay to start the generator (this won’t be relevant in this test, but verify the setting). Time delay to transfer the load after generator availability. Time delay for re-transfer to utility after power restoration.

Adjust (if needed)

If necessary, adjust these time delays according to your project requirements. Document any changes you make.7.

Alarms and Indicators



Test Alarm Functionality

If the ATS has alarm outputs (e.g., low voltage, overcurrent, transfer failure), test these alarm functions by simulating the conditions that would trigger them. This might involve temporarily disconnecting a voltage sensor or manipulating a current transformer signal (use extreme caution with CTs – never open-circuit a CT when current is flowing).

Verify Indicator Lights

Confirm that all indicator lights on the ATS are functioning correctly.8.

Review and Documentation

Document all test steps, observations, and results. Note any discrepancies or issues encountered during testing. Create a written report summarizing the ATS functionality and any adjustments made.

Important Considerations and Troubleshooting



ATS Settings

Many ATS units have adjustable settings for voltage thresholds, time delays, and other parameters. Ensure that these settings are configured correctly for your application.

Wiring Diagrams

Refer to the ASCO 7000 wiring diagram throughout the testing process. Incorrect wiring can damage the ATS or create a safety hazard.

Troubleshooting

If the ATS does not respond as expected, consult the ASCO 7000 troubleshooting guide for possible causes and solutions.

Neutral and Grounding

Pay close attention to neutral and grounding connections. Improper grounding can cause problems with the ATS operation and can create a safety hazard.

Hysteresis

ATS units use hysteresis in their voltage sensing circuits. This means that the voltage at which the ATS initiates a transfer may be slightly different from the voltage at which it returns to the utility source. This is normal and prevents the ATS from "chattering" during voltage fluctuations.

Exercise Timer

The ASCO 7000 may have an exercise timer that is used to automatically start and run the generator for a set period of time. Make sure to disable the exercise timer during testing (or understand how it will affect your results).

Key Takeaways



Safety First

Lockout/Tagout and qualified personnel are paramount.

Read the Manual

The ASCO manual is your bible.

Control Wiring Simulation

The safest and most controlled method to simulate utility power failure.*

Documentation: Thorough documentation is crucial for future reference and troubleshooting.By following these steps and taking the necessary precautions, you can safely and effectively test the functionality of the ASCO 7000 ATS without having the standby generator physically connected. This will help you ensure that the ATS is ready to operate properly when the generator is commissioned. Flag for review