AUTO SOURCE CHANGEOVER SYSTEM

1. General

1.1 The remotely operated transfer switching equipment based on circuit breakers or switch disconnectors (often referred to as a source changeover system) destined to electrical distributions shall be conform to the standards IEC 60947-1 and IEC 60947-6-1 and to the national corresponding standards in member states (VDE 0660-100 and 0660-114, BS EN 60947-1 and 60947-6-1, NF EN 60947-1 and 60947-6-1), latest versions.

1.2 The transfer switch equipment will be of a derived type. It shall use products complying with the standards IEC 60947-2, IEC 60947-3 and IEC 60947-4-1.

1.3 By construction, the remotely operated transfer switch equipment shall offer in the optimum security conditions, the following possibilities: either the control by an automatism designed by the customer, or the control by an automatism designed by the manufacturer.

1.4 The transfer switch equipment shall have the following characteristics:
1.4.1 a rated impulse withstand voltage (Uimp) of 8kV
1.4.2 a rated insulation voltage (Ui) of 800V AC
1.4.3 a rated operation voltage (Ue) of 550V AC or 690V AC

1.5 The transfer switch equipment shall have 3 pole or 4 pole variants, the number of poles for the normal and the replacement circuit breakers or switch disconnectors being compulsorily the same.

1.6 The transfer switch equipment will be used for frequencies of 50/60 Hz.
1.7 By construction, the transfer switch equipment shall provide 3 stable positions :
1.7.1 Normal circuit breaker OPEN,
1.7.2 CLOSED,
1.7.3 Replacement circuit breaker OPEN

1.8 The OFF position will be an isolation position. The transfer switch equipment shall be suitable for isolation according to the standards IEC 60947-1, IEC 60947-2 § 7.1.7, for transfer switch equipment based on circuit breakers, and IEC 60947-3 §7.2.7, for transfer switch equipment based on switch disconnectors, and for Overvoltage Category IV, up to a rated impulse voltage of 690V according to IEC 60664-1. It shall also be possible to lock each circuit breaker or switch disconnector in the OPEN position.

1.9 It shall be also possible to operate manually the transfer switch equipment in case of lack of control voltage.

1.10 By construction, the transfer switch equipment shall have a class II insulation, according to IEC 60664-1, between the front face and the internal power circuits.

1.11 The transfer switch equipment shall have a control voltage of from 48 to 415V AC (50/60 Hz) or 440V AC (60Hz only ) or 24 to 250V DC.

1.12 The transfer switch equipment shall have performances according to the utilization category AC3 2B according to the standard IEC 60947-6-1.

1.13 The remotely operated transfer switch equipment based on circuit breakers or switch
disconnectors shall be of a mechanical interlocking type and an electrical interlocking type, in order to avoid any coupling possibility of the normal and replacement source.

1.14 A combination of circuit breakers having different breaking capacities and switch disconnectors shall be possible.

1.15 In the case of utilization of a switch disconnector, the upstream protection shall have to be specified by the manufacturer.

1.16 For all the allowed operating voltages and frequencies, the transfer switch equipment shall operate in a temperature range of –25°C to +70°C

2. Construction, operation and Environment

2.1 The transfer switch equipment shall be conceived according to the principles of Eco-conception defined by the standard ISO 14062.

2.2 The transfer switch equipment shall contain compulsorily an electrical interlocking system.

2.3 The transfer switch equipment shall contain 2 circuit-breakers or switch disconnectors (fixed or withdrawable), installed on a base plate. The 2 circuit breakers or switch disconnectors can be mechanically interconnected.

2.4 The mechanical locking of the 2 fixed or withdrawable circuit-breakers or switch disconnectors shall be possible.

2.5 The transfer switch equipment based on circuit-breakers shall ensure the protection against overloads and short-circuits.

2.6 The transfer switch equipment shall also contain an earth-leakage protection, by the means of an incorporated or separately mounted residual current device.

2.7 In order to ensure the isolation suitability according to IEC 60947-1, IEC 60947-2, §7.2.7, for transfer switch equipment based on circuit breakers and IEC 60947-3 §7.2.7 for transfer switch equipment based on switch disconnectors, the mechanism shall be designed such that:
2.7.1 the toggles or handles can only be in OFF position (O) if the power contacts are all
actually separated,
2.7.2 in OFF position, the toggles or handles shall indicate the isolation position.

2.8 Isolation shall be provided by a double break on the main circuit.

2.9 The minimum operating transfer time for the contacts of the transfer switch equipment will be less than 1 second.

3. Durability

3.1 The mechanical durability on the Normal Open – Replacement Close – Replacement Open –Normal Close (NO-RC-RO-NC) shall be:
3.1.1  10000 cycles, for the ratings <= to 250A
3.1.2  8000 cycles, for higher ratings.

3.2 The electrical durability on the NO-RC-RO-NC cycles for the operating voltages <=440V shall be:
3.2.1  10000 cycles, for the ratings <= to 250A
3.2.2  3000 cycles, for the ratings 400A-630A

3.3 The electrical durability on the NO-RC-RO-NC cycles for higher operating voltages shall be of 1500 cycles.

4. Auxiliaries

4.1 It shall be possible to equip the transfer switch equipment with a downstream coupling device, simplifying the connection between the bars and the cables with lugs. It shall allow the association of circuit breakers or switch disconnectors of identical dimensions and shall be used on fixed versions only.

4.2 Every circuit-breaker or switch disconnector of the transfer switch equipment shall be equipped with auxiliary contacts et alarm contacts.

4.3 The transfer switch equipment shall be equipped with voltage presence indicators and it shall be possible to equip it with permanent insulation monitoring devices.