Lightning Blowing Relay Contact Was Found In V-Guard Voltage Stabilizer
This Voltage Stabilizer, which was set right by me in April, 2023, revisited me in December, 2023 stating that the output was missing, after a lightning attack in their area. I opened the unit and did a cleaning and checked up. When I applied the power, the input was switching on with the LED Lit. But the output was not getting on after the delay, though the relay switching on. Then when I shorted the contacts, the output came, indicating that the relay contacts were the issue. I had the two-pole-two-way Relay and replaced it. To replace this, we need to remove the fixing plate from the transformer, loosening the nut and bolt, and then remove the relay holding screw.
Since I had already replaced all the capacitors, one transistor and potentiometer during its last visit and retouched the board, there was no further work in this unit, as all the diodes, transistors, capacitors and resistors were found to be ok.
After replacing the relay, I tested the unit and it got switched on after a delay and I tested it for more than an hour before closing the cover.
Mission accomplished bringing satisfaction to the customer and getting it collected to the bag on my side.
This article was prepared for you by Parasuraman Subramanian from India. He is 74 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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Albert van Bemmelen
May 11, 2024 at 4:19 pm
I guess that the relays that protect the output voltage from getting out of range are not sufficiently protected from burning in on their contacts although any high voltage lightning surge instantly would kill any semiconductor no doubt.
Which probably could be prevented with a single two-wire snubber circuit consisting out of a resistor and capacitor that are connected in parallel over the switching contacts of the relay. That RC snubber can also be bought as one component with both parts integrated. But if that absorption or anti-jamming circuit already was added to this voltage regulator device it probably would have been destroyer by the lightning too. They often also are used in thyristor and triac switching circuits. And apparently Varistors are inefficient in preventing voltage and current deviations still resulting in relay contact adhesion.
Parasuraman S
May 12, 2024 at 10:56 am
Many thanks for your expert suggestions! These Voltage Stabilizers are made very cheap with minimum components to surive in the market, as there is tough competition with Chinese products flooded around. So, such protectors are not included. But we can find such circuits in UPS.
Yogesh Panchal
May 11, 2024 at 6:03 pm
Good Job! Sir,
Parasuraman S
May 12, 2024 at 10:57 am
Many thanks, dear Yogesh!
Waleed Rishmawi
May 12, 2024 at 12:53 pm
That is an ugly looking relay and I am glad you found a replacement for it. Thanks for sharing and be blessed my friend
Parasuraman S
May 12, 2024 at 3:55 pm
Many thanks, dear friend!
Imoudu.O
May 13, 2024 at 4:17 am
I repair V.S quite often and i haven't come across this type. What is that black thing that looks like acid-lead battery there?
Parasuraman S
May 13, 2024 at 12:56 pm
That is the new relay I fixed in place of the defective one.