Arc flash accidents are no joke.
It’s estimated that around 30,000 arc flash incidents occur every year in the United States. (That roughly translates to about five to ten accidents each day.) These accidents mean burns, hospitalizations, and even deaths. Certainly not something to be taken lightly.
When it comes to transformer maintenance, arc flash is a critical consideration. Taking routine oil samples is an important part of knowing the overall health of your transformer. However, taking these samples from inside the padmount cabinet can be both inconvenient and dangerous. Plus, powering down the transformer is often not an option for most companies.
So what’s the solution? Easy. External sample ports.
Installing external ports for sampling transformer oil is a simple way to prevent downtime and protect employees. You’ll be able to take samples without getting anywhere near the live cables inside the cabinet. And you will have no reason to power down the unit and incur lost revenue.
Also, these external ports are designed to be added to existing transformers where the sampling valve is already located inside the secondary cabinet. No need to attempt moving the valves to the cabinet exterior.
Maddox has external sample kits in stock ready to ship to you.
This simple step-by-step guide below will lead you through the easy installation process.
First, let’s take a closer look at the kit itself.
What is an external sample kit?
The external sample kit is the set of parts for installing two sample ports on the outside of your transformer cabinet. You’ll place a nitrogen sample port near the top of the cabinet, and an oil sample port near the base of the cabinet. Let’s look at the kit parts and the installation process.
Installing the External Sample Kit
You’ll want to gather the items in the kit along with a few extra tools.
External Sample Kit Parts
- Stainless steel/teflon hose
- Recessed ports
- Ferrule fittings
- Hose connectors
- Hose end pieces
- ¼” fittings
- Pressure relief valve
- Gas sampler valve
- Unit information card
The Tools You’ll Need
- Gloves
- Measuring tape
- Drill with a 3/16” bit
- 3.5” hole cutter
- Angle grinder
- PATFE Pipe tape and sealant
- Wrench with 9/16” and 1” heads
- Electrical tape
- Starhead screwdriver
- Riveter with 3/16” rivets and washers
- Silicone
Take a look at the eleven steps for installing external sample kits below. Or…you can check out our demo video on our YouTube channel!
1. Choose the locations for each sample port.
Select locations on the cabinet exterior for both the oil sample port and the nitrogen sample port. We recommend placing the oil sample port about 10” from the ground to make room for an oil pan underneath the valve. You can place the top port wherever is most convenient for you.
2. Drill the port locations.
Make holes for both ports using a drill with a 3.5” hole saw.
3. Seal and secure the test ports.
3.1 Drill the Rivet Holes
While holding the new port in place, drill 3/16” holes for the rivets that will secure the port.
3.2 Apply the Silicone
Place a ring of silicone around the inside of the oil sample port. The silicone will act as an airtight adhesive to prevent any water or dust from getting into the transformer. We recommend using a generous amount of silicone, but making sure to wipe away any excess before the silicone dries.
3.3 Secure the Port
Secure the port to the outer cabinet wall using the pop rivets.
3.4 Repeat the process for the nitrogen sample port.
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4. Replace the nitrogen fill valve.
Replace the old nitrogen fill valve with the ¼” fitting included in the kit. You will want to coat the fitting with the thread tape coated in the blue sealant. Once inserted, tighten the fitting with the wrench.
5. Assemble the transfer hoses.
Follow the steps below to correctly measure, cut, and install the transfer hoses.
5.1 Measure the space needed between the internal nitrogen valve and the newly placed nitrogen sample port.
5.2 Measure the appropriate length of hose, and mark off the ends with the electrical tape.
5.3 Add the fitting covers from the kit onto the hose.
5.4 Cut the hose using the angle grinder.
5.5 Insert the ferrules on each end of the hose.
Be sure to clean out any loose debris in the fitting covers.
5.6 Attach the fittings to the ends of the hose, and tighten them with the wrench.
5.7 Repeat this process for the oil sample hose.
6. Install the new interior fittings.
After you make sure that the oil drain nozzle is closed, remove the old oil drain plug inside the transformer cabinet. Next, apply the thread tape coated in the blue sealant to the new 1” fitting. Insert the fitting, and tighten with the wrench. Next, insert the ⅜” fitting also with the thread tape coated in the blue sealant.
7. Connect both hoses.
Nitrogen Hose
Connect and tighten the nitrogen sample hose to the new nitrogen port inside the transformer cabinet.
Oil Sample Hose
Next, connect and tighten the oil sample hose to the new oil port inside the cabinet. With both hoses, make sure you leave enough slack so that cables easily fit around the hoses.
8. Install the new exterior fittings.
Attach the oil sample port fitting coated with the thread tape and blue sealant. Tighten it with the socket wrench. Then, attach the outside nitrogen sample port fitting coated with the same sealant, and tighten it with the socket wrench.
9. Test the oil port and document the results.
Open the bottom valve and watch for a consistent flow of oil. Document the test findings on the included nameplate card and place the card inside the oil sample port assembly. Be sure to close the port using the included cover.
10. Re-pressurize the nitrogen.
Using the top external sample valve, refill the nitrogen tank to approximately 5-PSI. Then, place the cover on the top port.
11. Check for leaks.
Lastly, spray the nitrogen hose and port with soapy water. Any bubbles you see will indicate a leak. Also, remember to ensure the cover on the top valve is tightly closed each time you open it.
Maddox Has External Sample Kits
These external ports will make your transformer maintenance much easier and avoid the risk of arc flash. You’ll protect your company from downtime, and protect your employees from potential injuries. (And let’s be real… no one enjoys twisting and turning in between large bundles of live cables.)
We stock these external sample kits and can ship them out to your projects. Fill out the form below to enhance the safety of your transformer maintenance experience.
