SW80 Series
of D.C. Contactors

The SW80 series of contactors has been designed for direct current loads, particularly motors as used on small electric vehicles such as light industrial trucks, powered invalid cars etc. They have double breaking main contacts with silver alloy contact tips, which are weld resistant, hard wearing and have excellent conductivity.

The range comprises: Single Pole, on/off types (SW80), Double Pole, on/off types (SW82), Single Pole normally closed types (SW85), and paired versions of these for motor reversing (SW822, SW88 and DC88 types)

Compact Size
The contactors are compact in size and are fully serviceable, excluding 'P' versions, with a full range of spare parts available. They are economical in price and compare favourably with sealed automotive style solenoid switches which cannot be serviced or inspected for contact wear.

Easy Installation
Mounting is by means of 4mm tapped holes in the switch frame together with a range of mounting brackets complete with screws and washers. Coil connections are by means of 6mm spades of which two are supplied per terminal.

Contactor types DC88, DC92, SW822, SW86, SW88, SW90, SW92 and SW93 are supplied as an assembly which includes a double mounting bracket as a standard feature. Mounting attitudes are detailed in the drawings within this web site.

Operating Coils
Coil voltages ranging from 6 to 240 volts are available and these are wound for D.C. operation. However, coils can be fitted with a bridge rectifier for use from A.C. supplies.

Coils are normally wound for intermittent duty (up to 70% "on" time) but continuous duty versions (100%) are also available. Pull-in voltages are approximately 60% and 66% of the rated voltage for intermittent and continuously rated types respectively. Drop-out voltage is normally 10% of rated voltage.

Variations from these pull-in and drop-out figures can be engineered to suit particular applications.

Contactor Pairs
The contactors can be mounted in pairs on a common bracket together with inter-connecting electrical links. The most important of these arrangements are the motor reversing circuits provided by the SW88, DC88 and SW822 contactor pairs.

The SW88 and DC88 types have a built in failsafe so that if both coils are energised simultaneously the contact design creates an open circuit. The SW822 types have fast drop-out times (approx. 5mS) and relatively slow pull-in times (approx. 20mS). Therefore motor direction changes can be undertaken without risk of all contacts being closed at the same time. However, certain types of coil suppression such as diodes substantially increase drop-out times and care must be taken to ensure suitable suppression is fitted, e.g. diode and resistor in series.