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ODS Control and Selector Switches

ODS Control and Selector Switches

IntroductionThis publication provides design, application and ordering information for the ALSTOM range of ODS control, auxiliary and instrument switches. The ODS range has been manufactured for over twenty five years and is well proven in a wide variety of applications and operating conditions.

ApprovalsODS switches are approved by CEGB to ES150-18 Duty II & Life Classes I, II & III Lloyds Register of Shipping

Ordering ProcedureContact arrangements for most standard types are detailed on pages 9 to 13. Please specify requirements by filling in the whole of the switch ordering sheet provided at the back of this publication. Further copies of this form are available on request although you may prefer to produce your own duplicate copies.


Features 30A contact rating

Benefits Negates the use of ancillary contactors for many heavy current switching applications Critical switching operations can be achieved using one switch preventing possible errors when using more switches Can be used for duties having many functions Switches suitable for ac, dc and small signal applications Switches available for both selector and control applications from the same range Meets all required safety standards quenching properties High reliability and durability positive electrical connection Suitable for use on all styles of switchboard Large handles provide positive switch operation when multiple contacts are used Key operated switches provide added security

Up to 60 contacts on one switch

Up to eight switch positions

Choice of contact duties

Choice of stayput or spring return

Flame retardant material with arc

Silver cadmium oxide contacts for

Choice of 13 handles including key operated

Barrel locks or padlocking facility

Prevents unauthorised use available Provides additional contacts when used with circuit breakers Last position indicator displays status of breaker Lost motion contacts provide an electrical means of displaying status of circuit breaker and ensures breaker cannot be opened or closed twice in succession Provides easily readable display of switch duty

Auxiliary switch available with universal driver lever Last position indicator and lost motion (slip) contacts available for circuit breaker control applications

Engraved escutcheon


ConstructionThe ODS switch has been designed on the pack principle, each individual pack containing electrically independent double break contacts and a mechanical operating cam, driven by a common shaft. Up to 30 packs can be accommodated on a single switch giving a maximum of 60 electrical ways. More contacts can be accommodated, as required, by ganging two or more switches together. The individual switch packs which form the basis of the switch are moulded in a self extinguishing plastic compound with inherent arc quenching and high insulating properties. The contacts and associated moving parts are completely enclosed in the moulding giving a high degree of dust protection. The mechanism housing is moulded in fire resistant material and contains the mechanical parts necessary to provide the stay-put, spring return or lost motion switch actions.

ContactsEach pole provides a double electrical break by means of two fixed contacts and one moving bridge contact. Contacts have domed silver cadmium oxide buttons on the fixed parts and flat silver cadmium oxide buttons on the moving contact. The fixed copper terminal faces are tin plated to ensure a good electrical connection. See Figure 1. The contact bridge system comprises a moving contact attached to a cam follower. On operation of the switch the brass roller, part of the cam follower, follows the contours of the operating cam causing the contacts to open and close as required. Contact pressure is maintained by two springs acting on the contact bridge. The design of the ODS switch is such that make before break or break before make contact arrangements can be provided dependent upon the switch application.

Four classes of contact duty are available; Extra Light (gold plated), Light, Medium and Heavy duty. To determine which class of contact duty you require refer to contact data on page 15.

EscutcheonsIf required an escutcheon for mounting on the front of the panel can be provided. The escutcheon can be supplied blank or with customised engraving which must be stated at the time of order. A standard gravoply escutcheon is provided with a white background and black letters when engraved. Alternative colours are available on request please refer to factory.

Figure 1: ODS switch pack


HandlesSmall pointer type (MS) handles are normally fitted as standard to both control and instrument switches. Alternative handles are available as illustrated in Figure 2.













Figure 2: ODS switch handles 5

Locking FacilitiesThe following locking facilities can be provided on control switches.


Padlocking arrangements can be provided with either a pull to lock or a self locking push to release facility. See Figure 3. Locking can be achieved in any switch position or combinations thereof, by selection. The maximum diameter padlock hasp suitable for use with the switch is 4.7mm.

Figure 3: Padlockable ODS switch

Barrel locking

A barrel lock can be incorporated in the centre of the operating handle, lockable, by selection, in any of the switch positions. It can be supplied with either the key free when switch locked or unlocked or key free only when switch locked. See Figure 4.Figure 4: ODS switch with barrel lock

Key operated removable handle

Here the key acts as the handle to operate the switch. The key can be chosen to be removable in all or selected positions. See Figure 5.

Figure 5: Key operated ODS switch 6

Control and Instrument SwitchesThe following types of control instrument switch are available in the ODS range:Maintained contact

Spring return and lost motion switch

Sequence device

The maintained contact or stay-put switch is normally supplied for all instrument and selector switch applications. It is available with a 45 or 90 degree throw between positions.Spring return

This type of switch is divided into two parts. The front portion of the switch contains contacts requiring spring return action and the rear portion accommodating contacts for which the lost motion (slip contacts) facility is required. Using this facility, the relevant contacts are made in one of the nonneutral positions and remain made in that position until the switch is operated to the other non-neutral position. A maximum of 3 contacts can be made in any one non-neutral position.Stayput and Spring return switch

This device, used with a spring return mechanism, prevents two consecutive movements in the clockwise position from neutral.Auxiliary switches

Most control switches are manufactured with spring return to the original neutral position. They are used for circuit breaker control and other types of electrically controlled apparatus where momentary contact is required. The ODS spring return switch is designed with a 60 operating angle in either direction from the neutral position. A maximum of 10 contacts can be made in either non-neutral position.Spring return and last position indicator switch

The ODS auxiliary switch is normally operated by the action of the circuit breaker and provides auxiliary contacts for control and indication. A universal drive lever is available for use with the ODS auxiliary switch. This lever consists of two side members of aluminium alloy and two clamping plates. See Figure 7.

This switch can have up to three stay-put positions having a 90 degree operating angle, with up to two spring return positions having a 45 degree operating angle. Naturally, spring return will only be available at the extreme positions to which the switch will operate, hence the maximum of two.

A mechanical last position indicator can be fitted to a spring return switch and indicates the last position to which the switch was operated. See Figure 6.

Figure 6: ODS switch with last position indicator

Figure 7: ODS auxiliary switch with universal drive lever


Outline & Mounting DetailsThe detail given below indicates the space required behind panel to mount switches. Exact details of switches will be provided upon acknowledgement of order.

Panel mounting

ODS control instrument switches are mounted by four screws to panels of a maximum thickness of 6.35mm (0.25) inches. If switches exceed 200mm (8 inches) in length, a supporting bracket is advisable. Panel drilling details for most switches are as outlined in Figure 8. Exact detail for the switch you order will be provided upon acknowledgement.

2 off tapped bushes for M5 x 0.8 thread fixing screws 66.5

A 14.3 M4 terminals 15.9 3.0 to 6.4 Dimension A = (No. packs x 12.7 + 14.3mm) Mounting Panel Datum scribe (up for mounting) 19 Handle locking groove Auxiliary Switch

50.8 25.4

Rear view

Side view Stayput or spring return non lock switch 3.0 to 6.4 41.3 8 25 AS 12 AL 29 Mounting Panel

Panel hole for optional last position indicator. 6.0 Csk @ 90 incl to 8.0. AS 51 AL 89



4 Holes 5.5 Csk @ 90 to 10.0 on 70.0 PCD. Escutcheon mounting holes to suit fixing. (Escutcheon holes 4.2) Escutcheon outline




Stayput or spring return barrel lock or padlockable switch 3.0 to 6.4 69.8 8? Mountin