How load affects Power Pack performance
Proper Loading of Power Pack Reefer Generators
Are your reefer loading processes harming your power packs?
In a recent survey we asked the question, ‘What is your typical practice for connecting reefer plugs to your power pack?’ Possible choices included:
- We fill the receptacle panel then start the power pack.
- We connect one at a time while the power pack is running.
- We connect them in groups of 5 or more at a time.
While the number of responses varied between the choices, a significant number selected choice #1, indicating that loading the power pack’s receptacle panel with connections prior to generator start is the preferred choice.
It’s easy to understand, perishable cargo tends to move in large quantities. And with many reefers hitting the docks at any one time, the goal, of course, is to quickly get these refrigerated containers connected to power. But take a moment to consider that this technique may have the potential to cause damage to your equipment which could potentially render your cargo without any electrical power.
Why this is bad.
Loading too many reefer boxes at one time on a power pack can cause the engine to work excessively hard to catch up to the required load. In the meantime, this may result in a drop in generator performance as the engine struggles to maintain sufficient power to meet this sudden demand. The results will be a reduction in hertz or electrical frequency causing potential damage to the generator’s voltage regulator. Loss of frequency can flow downstream to the reefer causing damage to refrigeration compressors. Additionally, there is added stress on the fuel delivery system to maintain engine power.
Either of these scenarios will leave you with a down machine, expensive repairs, and a load of perishable cargo without electrical power to maintain temperature.
How to avoid a problem
A systematic approach to loading Power Packs should be incorporated in order to avoid costly and time delaying damage.
Power Pack Loading Procedure, a Best Practice Approach
Every power pack is different and may have varying engine and generator configurations. It is strongly advised to review and understand all of the manufacturer’s operations manuals prior to beginning any power pack starting procedure.
Once started, here are some guidelines to ensure that you maintain the best performance from your power pack generator.
Applying load
Once power pack is properly started allow the engine to warm up for 5 minutes before loading reefers. Engage Main Breaker to ON Position.
For ESL Power receptacle panels:
- Insert a single reefer plug into the panel and secure locking ring by rotating clockwise
- Depress the plunger to energize receptacle.
- Repeat steps 1 and 2 above for each additional receptacle plug added to the panel.
Continue loading reefers until reaching a load of 50%. At this time, check amperage on the generator control panel. This is important to ensure that your generator is managing the load and working within optimal engine performance. Refer to the specifications of your power pack for total amperage information.
If at 50% capacity total amperage is under the specified maximum amperage of your power pack, then continue to load reefers gradually to full capacity, but continue to monitor the ammeter.
If amperage is OVER the maximum amperage STOP LOADING and wait for refrigerated container compressors to cycle before continuing to load more.
Loading too many reefers, especially hot reefers, at any one time may cause the amperage draw to exceed the limitations of your power pack.
Maximum amperages vary depending on the specifications of your power pack. If you are unclear on the maximum amps for your power pack, contact Power Pool Plus for information. Operating a power pack at near max amp rating should be monitored closely to avoid tripping main circuit breaker and losing all connected reefers.
A special note on loading: At minimum, there should always be at least a load of 25% of total panel capacity. In other words, if operating a 40 plug power pack, minimum load will be 10 reefers or 8 for a 30 plug machine. This will protect your power pack in 2 ways:
- Avoid the damaging effects of wetstacking – thick black exhaust smoke.
- Allow a more efficient use of your power pack. More reefers attached to your power pack means less fuel burn per reefer – which will save you money.
Unexpected shut down while connected to full load of reefers
Should an unexpected engine shut down occur, either through a run-fault event or manual stop, never perform a re-start while connect to a full load of refrigerated containers. Instead, load should be removed from the power pack and brought back on gradually. Best practice would be; de-energize ALL ESL receptacles, ensure that the main breaker is CLOSED, and re-start the power pack. At this time bring reefers back on line following the procedure highlighted above by energizing the ESL receptacles individually until all are successfully back online.
Manually shutting down an operating Power Pack
Often times, out of convenience, bad habits, or simply insufficient operator instruction, emergency stop (E-stop) buttons are routinely used to shut down a running power pack.
Emergency stop buttons should only be used for emergency situations, such as pending harm to personnel or equipment.
Using E-stop buttons as a regular means of power pack shut down can cause damage to the engine and generator components by not allowing a proper disconnection of electrical current to the load and necessary slow cool down of the engine.
Instead, follow this procedure,
- Open main generator circuit breaker
- Allow engine to cool down for 10 minutes
- Press the stop button located on the generator control panel. The generator will then stop. Some power packs have a built in shut down procedure that initiates upon pressing the stop button on the Control Panel. Check your Owner’s manual for specific information on your power pack design characteristics.
In short, unless it is an actual emergency, use the stop button located on the Control Panel and NOT the Emergency Stop buttons.
Wrapping it up
Each Power Pack is different with unique engine kVA and kW output. But the process for loading them to protect the Power Pack from overloading is the same. Following these quick and easy steps will ensure long lasting performance from your reefer power solution.
Power Pack maintenance doesn’t begin and end with oil changes. It starts with proper machine operation. No matter if your operation handles chilled loads, frozen loads, or pre-trips hot reefer boxes, Power Pack performance can be greatly affected by the way in which load is applied. Following these procedures to ensure that you get the most out of your reefer power system.
For more details on power pack operations read: 7 Best Practices for Every Power Pack Operator.
Have questions?
Please contact us today to learn more.
How to Avoid Port Congestion?
Photo Credits: Michael Neelon/Alamy; Columbia Group
Recent port expansion projects around the world are a sign of the competitiveness to attract some of the newest and biggest container ships. What has been slower to keep pace is the supporting infrastructure in surrounding areas. Roadways leading in and out of terminal gates are creating truck traffic gridlock at many ports. Sensitive refrigerated cargo is at risk if not moved quickly.
As more and more port operators are turning to alternative methods for moving their cargo off terminal, barge service has become much more viable. Utilizing existing waterways, barges offer the ability to bypass this congestion by moving cargo from the main port to areas more easily accessible to trucking and rail.
This is especially important for refrigerated cargo where timing is critical.
Yet moving reefer by unmanned and unpowered barge can present a host of challenges for the reefer cargo operator.
Power challenges for the barge operator
- Conformity of reefer diesel generators, or power packs, to the business of container handling. The greater its design fits into the regular operation the faster barge loading and unloading can occur.
- Long transit times without the ability to refuel can present a major barrier to the barge operator.
- Limited space; tightly packed containers on barges leave little room for diesel powered generators to breathe.
- Proximity to salt air and water environments, especially during heavy seas, can be problematic for mechanical equipment.
- Generator failure while in transit is a recognized concern to maintaining operational success for the reefer barge operator.
Power Pool Plus has been addressing these challenges for nearly 30 years by engineering and building power pack designs that are Purpose Built to deliver a reliable and continuous reefer power supply over multiple days of unmanned overseas transit.
What Does it Mean to be Purpose-Built?
If you’re in the business of handling refrigerated cargo, then you know all too well about the constant reliance on electrical power to keep your perishable cargo fresh (at least while it's under your watch). The need for generators to supply this electric power is great.
Using standby generators that are designed for emergency use may not be the best solution for managing the harsh realities of the reefer cargo industry.
What’s required is a purpose-built solution that can provide substantial electrical supply in a robust package that fits neatly into the working environment of the shipping industry.
But what does Purpose-Built mean?
To be purpose-built a product must have the ability to complete a specific task so uniquely that every aspect of its design takes the following elements into account:
- How it is going to be used? (Application)
- Where it will be used? (Environment)
- Who will be using it? (Safety)
- When it will be used? (Time Frame)
Power Packs, generators designed for powering refrigerated containers, are an example of such a product. But not all power packs are created equal. Simply being called a Power Pack does not make it purpose-built for reefer cargo application.
Power Pool Plus takes all of the above elements into consideration when designing power packs.
How it will be used (Application)
Our Power Packs are designed to be easily handled in and around a port environment including ships and barges. Outfitted with both fork pockets and corner pockets our power packs can be easily moved or positioned by any heavy lift port equipment.
For use on a barge, space is limited. Yet maintaining proper airflow is critical to power pack performance. We take that into consideration while still allowing our machines to stack neatly between containers.
Where it will be used (Environment)
Uneven ground, constant repositioning, salt air/water, extreme heat and humidity, cold arctic waters – these are just some of the harsh realities of keeping the cold chain intact. Our power packs are designed and built with these considerations.
Who will be using it (Safety)
In ports things move fast and keeping people safe is priority #1. Power Pool Plus goes to great lengths to ensure this is met.
To reduce the risk of electric shock, we use only ESL’s line of safety interlock receptacle modules. This ensures safe handling of electric plug connections made at the Power Pack panel.
When it will be used (Time Frame)
How long will your power pack need to run unattended? Fuel delivery in ports can be a big problem. And on barges, it’s impossible until next port call. Our power packs are designed with standard 1000 gallon (3785l) fuel tanks ensuring long runtimes of 36 to 48 hours depending on use and application. Additionally, our on-board engine lubricant reserve tanks with automatic refilling are essential to avoid low oil engine shutdowns during unattended operation on sea or land.
Of course, these are just some of the standard purpose-built features that set Power Pool Plus apart.
Have a very unique requirement?
Our engineering team can design a purpose-built power pack specifically for you. Just let us know the details.
Weather Preparedness and Your Power Packs
No one knows with any certainty how this year's Hurricane Season will end up. The best we can do is plan and prepare. And each has its place.
Planning
When disaster does strike, ensuring that you have an uninterrupted supply of electrical power is essential. Understand what resources that are currently at your disposal is the first step. The power packs that you already employ for your reefer operation can also be effectively used to provide emergency electrical power to buildings*.
Preparing
Using your power packs for emergency building power means that maintenance can't wait. Many tropical storms provide little advance warning. So keeping them in top shape and ready to run 24/7 is essential. Putting off required preventative maintenance on your generators may result in an unexpected failure.
* Safety is paramount. Please refer to your local electrical experts before connecting any generator to a building's load.