earthing diagram (ed) benches - schneider electric ... · – 2 star-triangle three phase...

S.L.T.-TR22 Bench

Study and operate the protection features associated with the

neutral plans with manual

troubleshooting

ebau312

Tampon

www.schneider-electric.com/educationalequipments 3/11

S.L.T.-TR22 Bench

1. Presentation of the kit

� This bench illustrates the rationale underlying the current regulations and standards concerning the physical protection of individuals as regards the TN or TT systems (first working surface) and the IT system (second working surface).

1.1 Overview On each of the totally independent surfaces, 3 single or three-phase receivers have been represented, with protection devices based on magneto-thermal circuit-breaker, differential circuit-breakers, differential switches, contactors. Power resistors and a rehostat located in the base of the bench are connected to the panel by cables (supplied) fitted with safety jacks for operations under the supervision of a qualified teacher.

4/11 www.schneider-electric.com/educationalequipments

S.L.T.-TR22 Bench

1.2 Characteristics

� Mechanical characteristics Dimensions: height: 1700 mm, width: 700 mm, depth: 700 mm Weight: 120 kg

� Electrical characteristics ❑ The bench is powered by a 400 V three-phase electrical network with earth

power ≥ 4 kVA. ❑ Voltage: 400 V three-phase ± 10 % ❑ Frequency: 50 Hz ± 5 % ❑ Current: 16 A, connection by 3P + earth socket ❑ The conventional short-circuit current is set to 10 kA. ❑ Rated impulse withstand voltage: 2,5 kV ❑ Protection class: l ❑ The electrical network must be fitted with a RCD (Residual Current Device) of

sensitivity ≤ 30 mA of AC class upstream the bench (not supplied).

� Technical characteristics of built-in components ❑ Isolation controller

– Vigilohm TR22A 220-240V ❑ Transformers

– Transformer 48VA P : 230/400V S : 24 V – 2 Star-triangle three phase transformer

❑ Circuit breaker – Three pole magneto-thermal circuit-breaker 4 to 6,3A – Two pole magneto-thermal circuit-breaker 1A and 0,5A – Four pole circuit breaker 16A – Three pole circuit breaker 10A – Two pole circuit breaker 12A, 0,5 et 6A – Differential bipolar circuit breaker 240V 25A 10mA


S.L.T.-TR22 Bench

1.3 Functional description The S.L.T.-TR22 bench allows the users to perform exercises on the various neutral plans. The two surfaces may be used at the same time, one for TN and TT neutral plans exercises, the other for the IT neutral plan exercises. Two single-phase receivers (R1 and R2) and a three-phase receiver have been represented. It has been assumed, for the sake of clarity and to assist in training, that receivers are in premises of various classes. The R3 receiver is supposed to be installed in fire risk premises. The user can then perform the various exercises on the two surfaces of the bench as well as on the power resistors located in the base of the bench.


S.L.T.-TR22 Bench

2. Teaching

2.1 Teaching presentation � S.L.T.-TR22 Bench allows:

❑ Theoretical study of the various neutral plans. ❑ Circuit cabling and study of device responses ❑ On the IT neutral plan: manual troubleshooting system.

� It is intended to the following studies:

Professional High School University & Engineering school

Automated Systems Industrial Computing

❑ ❑

Monitoring and Regulation ❑ ❑ ❑ Electrical Engineering ❑ ❑ ❑ Engineering Equipment Energy ❑ ❑ ❑ Industrial Maintenance ❑ ❑ ❑ Automated Production ❑ ❑ ❑ Mechanical Industrial Automated Systems

❑ ❑ ❑

Miscellaneous Industrial Automated Systems

❑ ❑ ❑

� Exercises to be performed from the S.L.T.-TR22 bench:

The exercises are composed of a teacher document and a student document. ❑ TT neutral plan:

– Interconnection and earthing of groundings are necessary conditions but not sufficient to ensure protection.

– The magneto-thermal circuit breakers do not ensure the protection against the indirect contacts.

– The use of a RCD is a necessary condition but not sufficient to ensure protection (threshold selection).

– The use of a RCD is a necessary condition but not sufficient to ensure protection (RA maximum value).

– Selective activation by RCD located at various level. – The earthing connection values must be measured regularly. – Fire risk. – Mobile receivers.

❑ TN neutral plan:

– An earth fault leads to an overcurrent which is eliminated by standard circuit breakers.

– Does a given circuit-breaker ensure protection in every case? – What to do if the conditions are not fulfilled?


S.L.T.-TR22 Bench

❑ IT neutral plan:

– Interconnection and grounds earthing are necessary and sufficient conditions for protection in the case of first fault.

– Permanent insulation monitoring of the network with respect to the earth and indication of the first.

– Single fault: search for the faulty feeder by successive short opening of the various circuit-breakers.

– Single fault: search for the faulty feeder by injection of AC current at very low frequency.

– Double fault: circuit breaker protection is insufficient for long feeders (example p.8 to 10).

– Double fault: need to provide RCDs on long feeders.


S.L.T.-TR22 Bench

2.2 Teaching examples


S.L.T.-TR22 Bench


S.L.T.-TR22 Bench

3. Items provided with the kit

3.1 Equipment provided

� A ready-to-use S.L.T.-TR22 bench assembly with two double-sided working surface reference MDG99605. � A set of safety cables

3.2 Documentation

� A technical manual (reference MDG9AD604) � A tutorial handbook (reference MDG9AD605)

4. Name and address

Schneider Electric France Activité Didactique 3F 35 rue Joseph Monier CS 30323 92506 Rueil Malmaison - France “Indigo” phone No.: 0 825 012 999 http://www.schneider-electric.com/educationalequipments e-mail: [email protected]

earthing diagram (ed) benches - schneider electric ... · – 2 star-triangle three phase...

Documents