Sangamo Q551 Round Pattern Astro Zone 2 Time Switch 3 Pin 20A - Optional Early Off

The Sangamo Q551 is a round-pattern astro time switch designed for zone 2 lighting control, offering 24-hour programmable scheduling with astronomical time adjustment and optional early-off functionality. The unit connects via a 3-pin terminal arrangement and carries a 20A current rating, making it suitable for controlling street lighting, car park lighting, security lighting and commercial exterior illumination where switching times need to follow sunrise and sunset throughout the year.

Fitted in distribution boards, street furniture cabinets and outdoor control panels, the Q551 automatically adjusts switching times based on geographic location and date, compensating for seasonal variation in daylight hours without manual reprogramming. The optional early-off function allows the output to be switched off before the calculated sunset time, reducing energy consumption in areas where full-dark operation is not required. The 100-hour battery reserve maintains programming and clock accuracy during mains power interruptions.

The round dial face displays a 24-hour clock with red markings and brass-finished adjustment tabs that set the on/off switching windows. The transparent cover allows visual confirmation of the current time position and programmed settings without opening the enclosure. The 104mm diameter and 134mm depth fit standard panel cutouts used across the Sangamo range, allowing retrofits into existing installations without modifying panel metalwork.

Zone 2 classification indicates this time switch is designed for control circuits requiring two independent switching events per 24-hour period, typically used in applications where lighting operates during evening and early-morning periods with an off period during the core night hours.

Product Specification Sheet

Product Manual

What is the difference between zone 2 and other zone classifications?

Zone 2 time switches support two independent switching events per 24-hour period, allowing lighting to operate during evening and early-morning periods with an off period overnight. Zone 1 units offer a single on/off cycle per day, while higher zone numbers support more complex multi-switching schedules.

How does the astro function work?

The astro function calculates sunrise and sunset times based on the geographic location programmed into the unit and the current date. This automatically adjusts switching times throughout the year to match seasonal daylight variation, removing the need for manual clock changes.

What does the optional early-off feature do?

The early-off function allows the output to be switched off a set number of minutes before the calculated sunset time. This is used to reduce energy consumption in areas where lighting is not required during twilight periods.

How long does the battery reserve maintain programming?

The 100-hour battery reserve keeps the internal clock running and retains all programmed settings during mains power failures lasting up to approximately four days. The battery recharges automatically when mains power is restored.