Trip Circuit Supervision

> Title of presentation - Date - References3 3

Operating Principle


Trip Circuit Supervisionoperating principle

Mechanical Command

Supervision current



mechanical CommandTripping circuit

interruption

Disappearance of supervision

current



mechanical Command

Alarm


Applications


Trip Circuit SupervisionApplications

• Improve the security and availality of the tripping circuit by a permanent continuity control.

• In case of circuit interruption, an alarm is generated

• Without this control, the interrupted circuit will only be detected after a fault without correct clearance.


Trip Circuit SupervisionApplications• Applicable if the trip coil of circuit breaker is activated

with a DC polarity

• In other cases, an interruption of the trip circuit will cause an immediate trip.

• Special application cases must be studied when using auxiliairy tripping contacts or lock-out relays



• Will allow a reduction of cyclic maintenance costs

• Will allow a more important delay between real circuit breaker tests.These tests become only required for the mechanical part control of the CB



• Need to be coordinated with the circuit breaker manufacturer :

- The maximum permanent current depends on thecoil impedance,

- The maximum permanent current must not cause anycoil heating,

- The electrical scheme of the CB tripping circuitmust be in acordance with the selected tripcircuit supervision scheme


Comparison of different existing schemes


Trip Circuit SupervisionScheme n° 1

+

-

+

-

Rela

yC

ircu

it Br

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rAdvantages

2 cables only between relay and circuit breaker

Alarm

No trip circuit control if CB open

Disadvantages

Alarm

Rela

yC

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it Br

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r

Contct position when equipment energised

52a

52a


+

-

+

-

Alarm Alarm

(1) Avoid a Battery short circuit when the CB is already open but trip order still present.

(1)

Rela

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it Br

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r

Rela

yC

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it Br

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r

Advantages

2 cables only between relay and circuit breaker.

Wire up to the CB, whatever the position.

Disadvantages

No trip circuit control if CB open

Requires additional resistance into the CB control box (1)

52a

52a

52b

52b





+

-

+

-

Requires 3 wires between relay and CB.

Tripping cable between relay and CB not controlled if CB open

Disadvantages

Advantages

The trip coil is controlled whatever the CB position

Alarm Alarm

Rela

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it Br

eake

r

Rela

yC

ircu

it Br

eake

r

52a

52b

52a

52b



+

-

+

-

Advantages


Disadvantages


Alarm Alarm(1)

Rela

yC

ircu

it Br

eake

r

Rela

yC

ircu

it Br

eake

r

52a

52a


Tripping cable between relay and CB not controlled whatever the CB position (1) - only the coil is controlledContct position

when equipment energised

(1) if interrupted, the current value becomes identical of the current circulation when CB is open.



+

-

+

-

Advantages


Disadvantages

Tripping cable between relay and CB not controlled whatever the CB position (1) - only the coil is controlled.


Alarm Alarm

Rela

yC

ircu

it Br

eake

r

(1)

Rela

yC

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it Br

eake

r

52a

52a



+

-

+

-

Advantages

CB Tripping coil controlled whatever the CB position

Alarm Alarm Tripping cable between relay and CB controlled whatever the CB position

2 cables only between relay and circuit breaker.

(1)

Rela

yC

ircu

it Br

eake

r

Rela

yC

ircu

it Br

eake

r

52a

52b

Triping contact

Logic Input (Opto)

Disadvantages

Requires installation of additional resistance into the CB control box (1)

(1) avoid any damage of the tripping coil when trip order still present and circuit breaker already open.

52a

52b




Practical exemplewith overcurrent relays


Trip Circuit Supervision with overcurrent relays

Delay timer

Logical input (Opto)

Trip contact energised =1 if Opto does not detect any current during TSUP timer

ET

Opto

Trip contact energised

& Alarm trip circuit faulty

Avoid any intempestivealarm in case of permanent trip orders.


Trip Circuit Supervision with overcurrent relays - scheme 1

+

-

Alarm

Rela

yC

ircu

it Br

eake

r

52a

Overcurrent relay

Trip coil

Trip coil control


Trip Circuit Supervision with overcurrent relays - scheme 2

+

-

Alarme

Rela

yC

ircu

it Br

eake

r

52b

52a

Overcurrent relay

Trip coil and auxiliary contacts control

Trip coil Resistance


Trip Circuit Supervision with overcurrent relays - scheme 6 (optimal)

+

-

Alarme

Rela

yC

ircu

it Br

eake

r

52a

52b

Overcurrent relay

ResistanceTrip coil

Trip coil and auxiliary contacts ontrol whatever the CB position

Logical input


Practical Exemplewith Programmable scheme logics


+

-

52a

52b Release timer

Alarm

Rela

yD

isjo

ncte

ur

Trip Circuit Supervision with Programmable Scheme Logics (Px40 range

relay)



MVAX Trip Circuit Supervision Relay


Trip Circuit Supervision MVAX relays

2 types :

•MVAX 12 : Trip supply supervision only

•MVAX 21 : Complete trip circuit and supply supervision, with CB closed only

•MVAX 31 and MVAX 91:Complete trip circuit and supply supervision, with CB in either state

MVAX91 is 3 MVAX31 identical circuits in the same box.

MVAX91 is dedicated to single pole CB and MVAX31 is dedicated to 3 poles CB



MVAX31 / MVAX91 operation :

•CB healthy and CB closed, both units RL1 RL2 are energized

•If circuit is open or power supply fails, RL2 drops off and opens contact RL2-1 to de energize RL1

•When CB is open, RL3 is also energized via the NC auxiliary switch, and RL1 is held by contact RL3-1

•RL3 will detect abnormal trip circuit with CB open in a similar manner to RL2 with CB closed.

•RL units are delayed of 400ms



MVAX 31 connection diagram :



MVAX 91 connection diagram :



MVAX 31 External resistance values depending on supply voltage :

Caution : 4,1kOhm resistance can be of 2 resistance 8,2kOhm in parallel

Trip Circuit Supervision

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