Timer based switch for a power capacitor

[Harsh864]

TL;DR Summary

Switch On in evening and off at night

To cover transformer loss at no load and maintain pf, we are needing 6kvar at day time and 9 kvar at evening.

Is there any time based switch available, such that it can switch ON 3 kvar at evening, say 8:00pm and turn off automatically at 8:00AM morning

 

[anorlunda]

Have you studied the features of the circuit breaker you are currently using? It may have capabilities for remote logic inputs.

 

[Harsh864]

No it doesn't have logic input

 

[Asymptotic]

Summary: Switch On in evening and off at night

To cover transformer loss at no load and maintain pf, we are needing 6kvar at day time and 9 kvar at evening.

Is there any time based switch available, such that it can switch ON 3 kvar at evening, say 8:00pm and turn off automatically at 8:00AM morning

Sure, plenty of ways to do this, but it is difficult to say without a better understanding of the specifics. For example, if this is a 600V bank then size a contactor to suit (check the contactor manufacture's recommendations) and control the contactor with a 24 hour timer along the lines of the Intermatic pictured below, or program an intelligent relay such as a Siemens Logo! to do the job.

 

[Harsh864]

Sure, plenty of ways to do this, but it is difficult to say without a better understanding of the specifics. For example, if this is a 600V bank then size a contactor to suit (check the contactor manufacture's recommendations) and control the contactor with a 24 hour timer along the lines of the Intermatic pictured below, or program an intelligent relay such as a Siemens Logo! to do the job.
View attachment 244848

I considered this things, but this all are rated at 240vac, whereas our line is 415vac, 50hz, 3 phase.
The transformer is 500kva rating.

 

[Asymptotic]

I considered this things, but this all are rated at 240vac, whereas our line is 415vac, 50hz, 3 phase.
The transformer is 500kva rating.

Add a transformer to step down from 415V to whatever control voltage you desire.

 

[Harsh864]

Add a transformer to step down from 415V to whatever control voltage you desire.

Sir, this may sound good but how that tiny transformer will handle incoming current if there's is some load required at any time.?

I am more inclined towards the intermatic mechanical switch but the voltage should 415v-440v

 

[Baluncore]

I considered this things, but this all are rated at 240vac, whereas our line is 415vac, 50hz, 3 phase.

415 VAC, 3 Phase is actually three lines, each 240 VAC relative to the neutral, separated by 120° phase.

 

[Asymptotic]

Control voltage transformer need only be sized large enough to handle contactor coil inrush current (plus whatever else may be connected to it - indicating pilot lamps, timer, and whatnot).

Work back from the contactor specifications, for example, if the contactor coil is rated 220V, 70 VA inrush and the timer consumes 5VA, a transformer rated 150 VA will easily handle the load.

Have you looked into any Intermatic timer specs? I don't know what they may offer in 415V/50 Hz, but their 60 Hz timer product line includes 480V timer motor supply with 20 amp contacts rated for up to 480V AC operation, and will easily handle a contactor coil. Be sure if you use a motor-based timer like this that the motor is rated 50 Hz, or the timing will be thrown off.

 

[Harsh864]

Can I go without adding any transformer, sir.?

Things I need -
1. Capacitor duty contactor
2. Digital Timer
3. 3 kvar capacitor

Digital timer will be connected to contactor and will control it. It will turn on/off the contactor and Therefore the capacitor.
Digital timer will be connected to 1live wire and neutral phase.
Am I Right..??

We have these products available here -

https://www.havells.com/en/consumer.../digital-weekly-programmable-time-switch.html
https://www.bestomart.com/products/l-t-crono-digital-time-switch-1000010836?variant=9605099520057
https://www.bestomart.com/products/l-t-gic-time-switch-j648b1analog-version-1000009126?variant=33729359630&currency=INR&gclid=EAIaIQobChMI5aHc4b_h4gIVAmoqCh1Z7Q0EEAQYByABEgIV1fD_BwE

 

[Asymptotic]

Can I go without adding any transformer, sir.?

Sure, if you have a neutral line available, and the control components are rated 240V/50Hz.
You'll want to fuse the control circuit to prevent damage in case a short circuit failure of the timer or contactor coil occur.

Before you order parts and build the KVAR capacitor bank and controls have a qualified electrician look over your plans.

 

[Harsh864]

Sure, if you have a neutral line available, and the control components are rated 240V/50Hz.
You'll want to fuse the control circuit to prevent damage in case a short circuit failure of the timer

Yes neutral line available and will provide MCB.
Capacitor and it's contactor will be 415V/50hz
I hope that's not a issue.

Edit - sorry, I got your point. The contactor coil should be 230 vac, along with fuses/MCB.

Am I right.?

Is there any contactor available for such a low capacitor - 3kvar.?

 

[Asymptotic]

Is there any contactor available for such a low capacitor - 3kvar.?

Search "capacitor contactor selection", pick a manufacturer (ABB, Schneider, Siemens, etc) and study their catalogs.

Am I right.?

Best advice I can give you is have a qualified electrician look over your plans, and do the wiring. I think you have the general idea, but the nature of your questions suggest limited background in electrical applications.

 

[Harsh864]

Sure, I will be having a electrician doing the work.
Thanks a lot for helping me out @Asymptotic