Replacing a transformer at an electrical substation can cost millions, so companies like Serveron that make electrical substation monitoring equipment help electric utilities avoid unnecessary costs by alerting them about potential transformer failures.
Serveron equipment extracts dielectric oil from the transformer. The equipment searches for signs of oil breakdown and, if it's detected, the electric utility company dispatches maintenance crews to prevent transformer failures.
The Series 200 pump has no mechanical
seal. Flow rates for Serveron equipment are as low as 250 mL per minute.
The flow rate is linear with drive speed and is calibrated to the control
signal, so no flow meeter is required.
"The electric utility company would typically send a maintenance technician to remote locations every quarter for manually removing an oil sample from the transformer," explains Serveron's electrical engineer Rick Kobe. Then the utility sends the oil sample to a lab for analysis. "Getting the results back from the lab could take another few weeks," Kobe points out. "A lot can happen to a transformer in those few months."
Kobe adds that when oil in a transformer breaks down it becomes a potential danger. "If gas from the oil breakdown builds up in the oil and there's an arc, the transformer could explode."
Kobe and other Serveron employees wanted a better way for electric utilities to monitor their transformers, so they de-signed the equipment with an automatic sampler that circulates oil out of the transformer through a hollow-tube membrane and into a gas separation module for analysis. The equipment remotely monitors the oil every four hours and automatically alerts the electric utility if the chemical composition of the dielectric oil changes. The trace chemical elements that form within the transformer indicate that the transformer requires preventative maintenance.
Selecting the proper pump is important to the success of the new monitoring equipment design. Kobe wanted a pump that lasts a long time without maintenance because many transformers are in remote locations and it's costly to send maintenance crews. He considered rotary vane and piston pumps, but ended up choosing a Series 200 magnetic drive, suction-shoe gear pump from Micropump (Vancouver, WA). "One of the main reasons we selected the gear pump was because it has no mechanical seal," says Kobe. "That means no oil leaks and no expensive clean-ups."
"The magnetic drive is the key to the leak-free operation," explains Paul Johnson, an engineer at Micropump. The Series 200 pump uses two cylindrical magnets. The second magnet is attached to the outside of the motor and drives one magnet inside the pump. "There's no direct contact between the pump and the drive," says Johnson. "Therefore, no shaft seal is required that could cause a leak. Only a single O-ring is needed."
For more information about suction-shoe pumps from Micropump: Enter 536