Previous in Forum: Regarding Rotor Earth Fault Relay Problem   Next in Forum: Parallel Charge/Series Discharge of Batteries Using Modified Quadrupler
Close

Comments Format:






Change Mode
Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







Add Vote
7 comments
Rate Comments: Nested
tigerdon
Commentator

Join Date: Jun 2011
Posts: 79

GEMSTART 5 with Toroidal CBCT : Long Earth Fault Tripping Time on Instantaneous

05/04/2015 7:46 AM

Dear All,

We are having GEMSTART 5 relay with Toroidal CBCT (10A/0.0167mA) for LV Motor Earth Fault Protection in LV Switchboard (415V)

Setting in GEMSTART 5 as follows ;

Earth Fault Method : EF Input

Earth Fault CT Primary Rating :

Range 1.0 - 10.00 A

Value 10.00A

EF Protection Speed 1

Ignore Earth Fault At Start For 0.4 s

Remote Earth Fault Resets Enabled No

Earth Fault Trip Current Range 1.0 - 10.00 A

Earth Fault Trip Current Value 2.00 A

EF Trip Current During Startup 2.00 A

Delay To Detect Earth Fault 0.0 s

(Additional) Delay To Trip 0.0 s

Once we inject 2.2A in cable through CBCT via secondary injection we are getting EF tripping time of 300-400ms on instantaneous setting which is should be around 50ms

Anyone having faced same problem with Gemstart 5 & toroidal CBCT??

Any solution to above problem???

Regards,

T.D.
Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Good Answers:

These comments received enough positive votes to make them "good answers".
2
RAMConsult
Guru
Engineering Fields - Power Engineering - New Member

Join Date: May 2007
Location: NYC metropolitan area.
Posts: 3230
Good Answers: 444
#1

Re: GEMSTART 5 with Toroidal CBCT : Long Earth Fault Tripping Time on Instantaneous

05/04/2015 1:02 PM

Not quite sure which model you have, so I don't know what other inputs you have besides the CBCT, so I'm assuming that you bench testing the relay by powering it up, letting it stabilize, then putting a 2.2A step into it.

Let's consider what the relay logic sees; it goes from "no input" to 2.2A instantly, then waits 400msec to issue a trip.If so then it's operating properly by assuming that it's a cold start and the delay is to let any transients wash out. You think it should trip instantaneously because you injected a current above the threshold, the only problem is that "instantaneous" is missing the condition "after the motor has been running for awhile".

Change your test setup to first put some voltages on the input to tell the relay "the motor's been running for awhile" or inject a much lower current then increase it to 2.2A and see how long it takes to trip when you do the increase.

__________________
 “Tell me and I forget. Teach me and I remember. Involve me and I learn.” Ben Franklin.
Register to Reply Good Answer (Score 2)
No more Good Answers.
tigerdon
Commentator

Join Date: Jun 2011
Posts: 79
#2
In reply to #1

Re: GEMSTART 5 with Toroidal CBCT : Long Earth Fault Tripping Time on Instantaneous

05/04/2015 11:41 PM

I appreciate your response

We have GEMSTART 5.4 Relay for Motor Protection

For EF we only have Toroidal CBCT connected to 22 & 23 Terminal of GEMSTART

Test Condition as Follows:

- 3 phase supply cable connected to Gemstart Module passing through Toroidal CBCT

- We inject 2A balance three phase current using secondary injection kit

- Then we increase / inject 2.2A current in one phase in order to create unbalance current to be detected by Toroidal CBCT

- We are getting 300-400ms EF tripping time which is not instantaneous

Requesting your further advice

Regards,

T.D.
Register to Reply
Wal
Guru

Join Date: Jun 2011
Location: Phnom Penh
Posts: 4019
Good Answers: 102
#3

Re: GEMSTART 5 with Toroidal CBCT : Long Earth Fault Tripping Time on Instantaneous

05/05/2015 12:39 AM

It seems a little more than coincidental that the trip delay is close to the ignore fault at start value.

Have you tried altering the Ignore Earth Fault at start value to say 0 and retesting?

__________________
 Difficulty is not an obstacle it is merely an attribute.
Register to Reply
tigerdon
Commentator

Join Date: Jun 2011
Posts: 79
#4
In reply to #3

Re: GEMSTART 5 with Toroidal CBCT : Long Earth Fault Tripping Time on Instantaneous

05/05/2015 1:08 AM

Yes we have also tried making Ignore Earth Fault at start value = 0, But EF tripping time is same no change....
Register to Reply
Wal
Guru

Join Date: Jun 2011
Location: Phnom Penh
Posts: 4019
Good Answers: 102
#5

Re: GEMSTART 5 with Toroidal CBCT : Long Earth Fault Tripping Time on Instantaneous

05/05/2015 3:27 AM

Should trip if you drop a phase too.

Have you tried that instead of injecting additional current into 1 phase?

__________________
 Difficulty is not an obstacle it is merely an attribute.
Register to Reply
Crabtree
Guru

Join Date: Jul 2007
Location: Commissariat de Police, Nouvions, occupied France, 1942.
Posts: 2599
Good Answers: 77
#6

Re: GEMSTART 5 with Toroidal CBCT : Long Earth Fault Tripping Time on Instantaneous

05/05/2015 1:45 PM

I'd pick up the phone and talk it through with the manufacturer if it were me. Then, I'm funny that way.

__________________
 Good moaning!
Register to Reply
tigerdon
Commentator

Join Date: Jun 2011
Posts: 79
#7
In reply to #6

Re: GEMSTART 5 with Toroidal CBCT : Long Earth Fault Tripping Time on Instantaneous

05/06/2015 12:31 AM

These all common sense things u mentioned allready done.

I have already taken up with manufacturer and they confirmed it is not possible for GEMSTART to trip on EF in less than 200- to 300ms when current of 2.2A applied on setting of 2A EF setting

They also confirmed "if the current value is more than 100% ( EX: In= 2A; I tripping= 4 A ) the time trip shall be under 100ms"

However, as an electrical engineer, product supplied by manufacturer stating Instantaneous EF protection feature then it should perform the desire function. 200 to 300ms trip time cannot be treated as instantaneous isn't it???

I just wanted to find out if somebody have faced similar problem with GEMSTART or there is some issue with respect to Toroidal CBCT used for EF detection with GEMSTART

Regards,

T.D.
Register to Reply
Register to Reply
Have a Different Question?
7 comments

Good Answers:

These comments received enough positive votes to make them "good answers".
Copy to Clipboard

Users who posted comments:

Crabtree (1); RAMConsult (1); tigerdon (3); Wal (2)

Previous in Forum: Regarding Rotor Earth Fault Relay Problem   Next in Forum: Parallel Charge/Series Discharge of Batteries Using Modified Quadrupler

Advertisement

Got Something to Say?
Ask a Question
Start a Discussion

Search this Forum
Electrical Engineering:
Go

CR4 Sections
Aerospace
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education and Engineering Careers
Electrical Engineering
General Discussion
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering
Transportation

Site Directories
Forum Directory
Blog Directory
User Group Directory
RSS Feeds

CR4 Rules of Conduct
CR4 FAQ
Site Glossary

Who's Online (167 right now)
Show Members
Advertisement