Inspecting and maintaining standby generator sets the personal touch

Inspecting and Maintaining Standby Generator Sets: The Personal Touch

by Charles Schalk & David Burns

Knowledge is power - Sir Francis Bacon

Introduction Standby generator sets play a critical role, supplying backup power in case of a service interruption. Both reason and regulations dictate a regular schedule of inspection and testing. By taking a proactive rather than reactive approach to genset maintenance, you can ensure that emergency power will be there for you when you need it. While automatic exercising equipment is available, it is no substitute for the hands-on approach. A physical and visual inspection builds familiarity with your equipment, how it starts and performs, and what can be expected in an emergency.

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A weekly walk-around inspection takes about 30 minutes. Your owner’s manual will provide a task list for you to follow, so that your checking is consistent and complete. And the following will provide additional insight into maintenance processes and procedures to assist you in identifying ways of keeping your equipment in top working order.

Many simple checks can be performed yourself, and ought to be prior to each and every non-emergency starting of the engine. More involved tests, maintenance, and inspections can be complex and specialized. How much responsibility you wish to take on is worth some thought. And annual and triennial service is best performed by an expert. Whatever your experience, skill level, resources, and schedule, you may prefer to delegate many of these responsibilities to a service provider who can cover your individual needs. Where maintenance is concerned, pick and choose your battles.

Weekly Inspection Before your inspection even begins, you should have your task list and maintenance log in hand. Beyond that, you need only bring along a basic tool box and safety equipment. Always use proper safety equipment and follow a safety-first protocol.

Following is an example of a simple walk-around inspection, along with some suggestions to detect common issues.

Always record all inspections, fluid levels, test results, parts replacements, and repairs1.

EXTERNAL EXAMINATION The inspection begins with the approach to the unit.

Conduct a walk around of the exterior, checking for possible present and future issues. Be sure the surrounding area is free of blockages; clear away obstructions to the door, clear items from the surrounding area, trim back ingrown bushes and shrubs, and remove objects leaning on the unit.

Some problems can be anticipated and avoided.

For example, nearby trees whose overhanging limbs or growing root systems may eventually cause damage to the structure.

Examine the structure itself for damage: crumbling bricks, any signs of rust, pools of liquid, or burn marks. Verify proper, unobstructed intake and exhaust vent clearance. A simple stuck rain cap can let enough water in to cause thousands of dollars in damage.

INTERNAL EXAMINATION Enter the structure and make sure the interior is free of clutter such as loose tools, buckets, and rags.

Enclosures are not storage areas. Clear out any dead

leaves or trash which have found their way inside. Look for bees nests and spider’s webs.

Inspect for signs of rodent infestation: droppings, a urine smell, bedding or nesting. Often, rodents will nest in engine crevices or the valleys of V engines, drawn to the warmth. If found, locate the point of entry and secure it. Expanded metal or wire mesh made of stainless steel work well, but rodents can and will chew through galvanized metal wire. Clean up anything they’ve left behind and look carefully for any chewed cables.

They present a fire hazard and should be professionally replaced immediately.

Examine the floor for puddles or stains, which indicate leaks.

Locate the source. Check hoses and fittings for signs of leaks.

Take note of any burnt wires. If found, call your field rep to come out and investigate.

Check the control panel for any triggered alarms. When so alerted, make arrangements for qualified inspection and repair.

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Before Starting the Engine Any time you plan to start the generator engine, you should perform checks on the major components and systems.

Any of these critical systems can leave you stranded and dead in the water if they malfunction.

LUBE OIL Check the fittings for leakage and worn seals. Look for bulging or cracking hoses. Ensure the proper oil level using the dipstick. Anywhere between “Add” and “Full” is acceptable. Examine the oil itself for discoloration. A milky color suggests coolant is present in the oil, while extremely thin oil may be a sign of dilution by fuel.

BLOCK HEATER A block heater raises the coolant to a high temperature, causing it to circulate throughout the system and warm the engine cylinders. As a result, the genset is prepared for rapid starts during transition to standby power. In a cold start, the sudden temperature increase can expand the pistons faster than the cylinder linings.

This means that the engine will spend time and fuel getting up to the ideal operating temperature for which it was engineered. It could accelerate engine wear due to friction resulting from cold oil and different thermal expansion of the pistons and the cylinder liners. Because the optimal running temperature is much higher than ambient even in warm climates, the block heater for a standby generator should always be plugged in and running.2 Since the block heater spends more time active than the rest of the genset, it accumulates hours of operation relatively rapidly. Therefore it can wear out and need replacement more often. While a genset will be able to operate without a working block heater, it should replaced when possible.

To assess the block heater, check for leakage or corrosion on the housing and at fittings. Inspect clamps and hoses for wear.

Close and open the ball valves manually to verify they are able to function properly. Carefully, with a gloved hand, touch the upper hose and housing. They should be warm to the touch, but not hot.

If the block heater has rubber hoses, replace them as soon as possible with silicone. Rubber may become brittle from the heat of the coolant.

COOLANT SYSTEM Ensure a radiator guard is present and securely affixed. Look for any rust or corrosion on the guard. Make sure that the fan shroud is clear of obstruction.

Determine if the radiator fins are clear of dirt and blockages with a flashlight. Gently clear any foreign matter. Look for signs of coolant leakage in the fins.

Look for rubber particles in the area of the fan belt, suggesting it may be wearing out. Check the coolant hoses for cracks and leakage. Where the core tubes meet the upper and lower tanks is a common site for failure. If present, white powder around the tubes is the residue from the coolant additives solidifying—a sign that the core may be rotting out. If the genset uses a remote radiator system, check the fittings are sound and secure.

Make sure air intake and vent hoses are clear. Vent hoses are hot, and should be physically isolated.

Check the coolant levels are adequate using the Murphy gauge or sight glass. But use them as an indicator, not the final word. Hoses can plug up and give false readings of the radiator being full.

If the radiator starts to plug, the path of least resistance for the coolant will be through the Murphy switch. This causes the float to be drawn down, and as soon as

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the thermostats open, the engine will shut down. Once this happens, the coolant level will stabilize. At first glance, this may falsely appear to be a problem with the Murphy switch.

BATTERIES

Check for burnt wires in need of replacement. Make sure wires are not pinched. Look for places where wires are rubbing or chafing on metal. Inspect wiring harnesses, assuring they are in good order.

Inspect the generator windings for any signs of damage, burnt wires, or trapped objects.

Check the openings inside the generator. Make sure the air pathways are clear for proper cooling.

The genset stores its charge in wet cell Lead-acid batteries.

FUEL SYSTEM

Wear eye protection, gloves, and an apron. To test the batteries, remove the battery caps and check the electrolyte levels3. Log them.

Examine the battery cables and make sure they are clean, free of corrosion, not cracked, and tightly attached. Check the battery voltage. A strong battery should read about 26.5 volts.

Always keep a spare fuel filter. In an emergency, oil filters can be bypassed, air filters removed. But you must have a working fuel filter for the engine to operate.

“Maintenance free” batteries are used, so there is no need to add water. Over time, even in properly cared for batteries, sulfates from the battery acid will build up on the lead plates. When this happens, the battery will no longer be able to discharge sufficient current, and must be replaced.

ELECTRICAL SYSTEM Do a thorough examination of the entire wiring system.

Locate and drain the fuel sediment bowl. Be sure to close it afterwards. Inspect the fuel. If it is cloudy or sediment is present, it is time to change the fuel filter.

Check for any leaks, especially at couplings. Inspect the fuel tank structurally. Fill to about ¾ capacity if it is lower.

NOTE: Never fill the fuel tank greater than about ¾ capacity to allow for expansion.

AIR FILTER Check that the air filter is clear and in good shape.

Make sure that the canister is clean and unobstructed.

Starting Up and Running the Generator As part of your maintenance schedule, it is required that you periodically run the genset. This is necessary for testing purposes, for keeping the system operational and efficient, and for compliance with regulations.

Always wear ear protection and stand at the rear of the generator for safety.

GETTING STARTED 1. The starter should engage immediately and start the engine on the first crank cycle.

2. The engine should ramp up smoothly and quickly to its normal speed: usually 1,800 RPM. 3. Observe the exhaust: - Billowing white smoke: The engine is running cold. The block heater may be set too low, or be worn out. Or else the engine thermostat is stuck open. (The presence of water or coolant in the fuel

can also cause this, but should have already been ruled out.)

- Blue haze: The engine has had excessive no-load run time, resulting in wet stacking: uncombusted fuel or oil has accumulated in the exhaust system.

- Black smoke: Oil or unburnt fuel is present in the combustion chamber. Have the unit checked by a qualified technician.

4. Check for any exhaust leaks throughout the system.

Look for any issues at the exhaust manifold gasket.

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THE CONTROL PANEL 5. Check the oil pressure.

6. Allow the engine to run for 5 to 10 minutes, then check the coolant temperature.

7. Check the voltage, frequency, and current are near the rated system values.

8. Take note of any new alarms.

9. If the generator is equipped with an on-site load bank, turn it on and run the system.

SHUTTING DOWN It is important to prevent wet stacking when shutting down. Therefore one should “warm down”: bring the generator to a smooth, gradual stop.

The genset should only rarely be run without a load bank. It is important to perform a load bank test annually.

Be absolutely sure to return the main control switch to auto mode. This is a surprisingly common cause of generator failure.

Test all of the alarms and alarm lamps. If the fuel level has fallen, top it off to ¾ full. Record all information in your maintenance log. Do a final walkthrough, checking for any trouble signs that may have revealed themselves during operation.

Regulations, Diesel Particulate Filters, and Regeneration Acquiring and retaining a permit for use is conditional on compliance with industry maintenance standards. These standards can be enduring and are difficult to change. And they can often be inadequate for or counterproductive to optimal performance.

A weekly test run, periodic inspection, and an annual load bank test are common. Other schedules may be permitted, and are in some cases more desirable.

In order to comply with emissions regulations, many regions require a diesel particulate filter (DPF) be fitted to a generator set. The DPF is designed to capture carbon monoxide, hydrocarbons, and other particulate matter from the exhaust. Some carbon monoxide and hydrocarbons are converted into carbon dioxide and water by a catalytic coating on the filter, and allowed to pass through4.

However, over time captured particulates build up within the DPF, increasing backpressure to the engine.

Regulations often mandate backpressure, runtime, and temperature monitoring equipment be installed. As excessive backpressure will reduce performance, these monitors can be used to maintain efficient as well as safe operation.

Even where not required, more runtime may be permitted with a DPF installed.

CASE STUDY: Run Time and DPF Maintenance Requirements Backpressure monitoring, as per Bay Area Air Quality Management District (BAAQMD) permit conditions.

(From an actual permit.)

CONDITION # 23613 • The owner/operator shall install, operate, and properly maintain a backpressure monitor that notifies the owner / operator when the high backpressure limit of the engine is approached. [Basis: BAAQMD Regulation 2, Rule 5] • The owner/operator shall install, operate, and properly maintain the following monitoring equipment to assure compliance with parts 3, 4 and 5 of this condition.

- Temperature Monitor - Temperature Recorder - Hours of operation monitor [Basis: BAAQMD Regulation 2, Rule 6]

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• The diesel particulate filter must be regenerated after every 10 cold starts. [Basis: CARB Executive Order DE-06-00, BAAQMD Regulation 2, Rule 5] • The engine must operate at the load level required to achieve 400 degrees Celsius for a minimum of 30 minutes. Operation at lower temperature is allowed, but only for a limited duration. The maximum consecutive minutes of operation below 400 degrees Celsius is 300 minutes. [Basis: CARB Executive Order DE-06-003, BAAQMD Regulation 2, Rule 5] • The filter must be cleaned at least every 2,000 hours of operation. [Basis: CARB Executive Order DE-06-003, BAAQMD Regulation 2, Rule 5] Notice the following in the permit requirements: • The DPF must be regenerated after 10 starts.

• The genset is limited to 5 hours of no/low load runtime.

• The common practice of weekly start-up testing may exceed permit limits.

REGENERATION AND LOAD TESTING When certain backpressure or runtime thresholds are reached—as determined by the equipment manufacturer and by regulatory agencies—accumulated build up in the DPF is removed through a process called passive regeneration. Operating under load, the generator is run to reach a filter temperature of 400 degrees Celsius.

At this temperature, the trapped particulate matter is oxidized; turned into carbon dioxide and water. The result is a reduction in backpressure and a clean diesel particulate filter. This process takes time; not only to reach the correct temperature, but to completely burn off all particulate matter and restore backpressure.

A two hour load test is standard. But the typical two hour load test may not sufficiently clean out the DPF:

• The first half of a standard load test may do more harm than good, effectively increasing backpressure.

• The regeneration temperature must be reached and maintained throughout the load test to be effective.

• The load test must include backpressure monitoring and downloading the data recorder, which take time.

Therefore, the load test may require longer than the standard two hours. This means more machine hours and more fuel use.

FILTER REGENERATION: THE PROCEDURE Don’t merely start up the generator and begin testing.

To properly perform the procedure 1. Activate the load bank.

2. Warm up the generator.

3. Run the unit up to full load at 400 degrees Celsius.

4. Start the test.

Continue to run the generator for an additional hour to burn off carbon build up and avoid wet stacking.

Notice that during the standard test, the backpressure kept climbing during the lower load steps. By the time the DPF started regenerating (400 degrees Celsius), the load test was over.

The DPF was more plugged than before the test.

Standard Two Hour Load Test (actual reading)

Observe that in a proper load test, after the warm up, the genset was taken to full load. Backpressure started falling after regeneration began. It leveled off, showing that the DPF was as clean as it was going to get.

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Proper Load Test for DPF Regeneration (hypothetical reading)

Conclusion It is essential to know the specific needs of your particular system, and the regulations governing your location. Equally crucial is diligence; avoid complacency in your service routine. Preventative maintenance is key to a reliable emergency power system. Avoid the run-until-failure schedule, or your backup power might not be there when you need it most.

Where possible, inspections should be rotated among qualified staff members.

This will bring fresh eyes onto the situation, and prevent the process from becoming routine and cursory. Give serious consideration to outsourcing maintenance to a qualified professional. Be sure to choose a service provider familiar with the equipment and its particularities.

AUTHORS Charles Schalk is a Product Support Sales Representative for Peterson Power Systems. He has 22 years of sales and training experience. During that time he has worked in the field to assist and understand the role of technicians performing their jobs and interacting with customers, while teaching proper safety procedures and generator maintenance. In the last five years in the Power and HVAC arena, he has supported large hospital trauma centers, landmark data centers, and everything in between. After running a successful Power and HVAC division for 2 years, he joined Peterson Power Systems in January of 2012. In addition to completing the extensive Cat training program, he recently took part in a Brand Ambassador program presented by Mark Rittenberg of the Berkeley Executive Coaching Institute.

David Burns is a technical writer based out of the Washington, D.C. metropolitan area. He studied chemistry and mathematics at George Mason University. His services have been engaged by a number of trade organizations and industry groups.

REFERENCES 1 NFPA.110-2013 - Standard for Emergency and Standby Power Systems 8.3.3 A written schedule for routine maintenance and operational testing of the EPSS shall be established.

8.3.4 A permanent record of the EPSS inspections, tests, exercising, operation, and repairs shall be maintained and readily available.

8.3.4.1 The permanent record shall include the following: (1) The date of the maintenance report (2) Identification of the servicing personnel (3) Notation of any unsatisfactory condition and the corrective action taken, including parts replaced (4) Testing of any repair for the time as recommended by the manufacturer 2 “Thermal Considerations for High Performance Engines.” Engine Builder Magazine. 12 July 2012. Web. 16 Sept. 2014 <http://www.engine builder mag.com/2012/7/thermal-considerations-for-high-performance-engines>; 3 NFPA.110-2013 8.3.7 Storage batteries, including electrolyte levels or battery voltage, used in connection with systems shall be inspected weekly and maintained in full compliance with manufacturer’s specifications.

8.3.7.2 Defective batteries shall be replaced immediately upon discovery of defects.

4 “Maintaining Your Generator’s Diesel Particulate Filter.” Peterson Power. Peterson, Inc., 2012. Web. 16 Sep 2014. <http://www.petersonpower.com/emissions/maintaining-your-diesel-particulate-filter>.

ACKNOWLEDGEMENTS Portions of material reprinted with permission from NFPA.110-2013 Copyright 2012, 2013 edition, National Fire Protection Association

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