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Case Study
Data of a control device was lost even with a UPS... Why?

A UPS with Li-ion battery solved a long-unsolved problem!

Food Manufacturer Company A (500 Employees)
Problem
  • Company A had a problem of a control device restarting over and over for unknown reasons even though a UPS was installed.
  • It was unlikely a power problem as a UPS was used, so they assumed the problem was caused by noise and took countermeasures, which did not improve the situation.
  • The operation panel was hard to see, and alarms were often overlooked.
Solution and Results
  • SANYO DENKI helped them measure the voltage in the factory, and identified the cause to be a momentary interruption in their standby UPS and its deteriorated lead-acid batteries.
  • The problem was solved by switching to a UPS with a power-quality mode.
  • The use of a UPS equipped with lithium-ion batteries greatly reduced the frequency of maintenance.

Tens of millions of tons of food is wasted annually in Japan. The government has enacted a law to promote the reduction of food loss, requiring consumers, food manufacturers and retailers, and food service providers to reduce food loss.

Problem

Food waste occurred every few months due to unexplained loss of control device data.

Traceability, quality control, and process control are essential for the management and control of food manufacturing.
Company A, which manufactures and sells food products, had cared to protect management information by using uninterruptible power supplies (UPS) as power backup for the control devices of their manufacturing equipment in case of emergency. However, despite the UPS, the company had repeatedly suffered data loss and food waste due to faulty control. Mr. K, a manufacturing engineer, explained:

"In the food manufacturing process, if any part of the data such as temperature, time, flow rate, etc. is lost, it affects the quality of food, so we had no choice but to dispose of the food. For some reason, these control devices would stop and restart, without anyone making them so, causing data to be lost, resulting in food waste." A power supply problem would be a reasonable cause of this problem, but Mr. K could not reach the conclusion yet.

"It was a serious problem, but it didn't occur frequently, so we had dealt with them by wasting food for many years. However, the frequency increased year by year and the Act on Promotion of Food Waste Reduction was issued a few years ago, so we started investigating this issue with more priority. Since a UPS was used, we had eliminated the possibility of power outage. Then we assumed that noise was the cause, and we took various measures for it, which never improved the situation."

Solution and Results

The cause was a "standby" UPS? SANYO DENKI proposed a hypothesis at the hearing

When Mr. K consulted a distributor about his problem, he was introduced to SANYO DENKI. After hearing about the problem, a sales representative of SANYO DENKI guessed that the cause of the problem was the use of a "standby" UPS.

SANYO DENKI's hypothesis:

(1) Power supply factor

• When a motor starts up in the factory, there occurs a temporary voltage drop, causing the UPS to switch to battery operation.
• An interruption of 5 ms occurs during transfer to battery operation.

(2) Manufacturing equipment factor

• With the capacitor of the DC power supply in the equipment aged, the electrolytic solution volatilizes, causing its ability to store electricity to deteriorate.
• A voltage drop also occurs in the DC power, causing the control device to restart.

"He guessed these factors might have caused the data losses, even though the UPS was used. He also pointed out that lead-acid batteries deteriorate under high temperatures, so the backup time might be shorter than the rated value," said Mr. K.

Use of a UPS with a power-quality mode improved the manufacturing trouble

In response to these suggestions, Company A carried out measurements in the factory with the support of SANYO DENKI. As a result, these hypotheses were proven.

"First of all, we detected frequent voltage drops of about 10%, which was just large enough to cause a UPS transfer to battery power. This means that transfers were about to happen at any moment! We also found one of our UPSs was raising a battery alarm, even though it had only been two years from the last battery replacement. It seemed that the UPS was installed in a way that the alarm indicator was hidden due to its size, causing the alarm to be overlooked," he explained.

SANYO DENKI's representative suggested they use SANUPS E11A-Li, a UPS with lithium-ion batteries, in the power-quality mode (Double Conversion mode).

What is the Double Conversion mode?

In this mode, the UPS supplies power through its inverter. Even in the event of an outage, the UPS keeps supplying power through the inverter, and transfer to battery never occurs. This is why this type of UPS is said to have the highest reliability.

How a double conversion online topology works (During normal operation)

How a double conversion online topology works (During an outage)

Use of the Li-ion UPS has eliminated battery replacement

Based on the measurement results, Company A decided to adopt the SANUPS E11A-Li UPS to replace their UPS in the factory. Mr. K described the effect of the new UPS as follows.

"It was more compact than the previous one, so it neatly fitted in the power distribution panel. Also, since the battery is now long-life lithium-ion battery, we don't have to do the periodic inspections or replacement anymore, unlike lead-acid batteries, which saves time and costs. Most importantly, we were able to identify the cause of the loss of data and solve the problem. Manufacturing process problems not only result in food loss, but also require time-consuming settings and adjustments for restarting operations. We are very grateful to SANYO DENKI for helping us improve work efficiency and reduce overtime work. We would like to consult them anothertime."

Date of publication: May 28, 2021

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