Isolatable Timer Relay | 24V DC with Key Switch | Adjustable Delay (0-5 Mins) | Red Boxed

FAQ

What is the primary purpose of the timer delay function on the 500-200KS?

The adjustable timer delay (0-5 minutes) is designed to manage false alarms by providing a grace period between fire alarm activation and the triggering of external alert systems such as autodiallers or monitoring station connections. This allows a responsible person time to investigate an alarm condition before remote signalling equipment is activated, helping to reduce unnecessary emergency service callouts and monitoring centre alerts whilst maintaining system compliance.

How does the keyswitch isolation feature work and when should it be used?

The keyswitch isolation facility allows installers and maintenance personnel to temporarily disable the relay output during routine system testing or maintenance work. When turned to the ISO position, the relay is prevented from operating under any circumstances, with a slow-pulsing yellow LED and buzzer (every 30 seconds or 3 seconds depending on DIL switch setting) providing continuous indication that the system is isolated. Critically, the keyswitch cannot be removed in the ISO position, ensuring the unit cannot be inadvertently left isolated after maintenance work is completed.

Can the 500-200KS be powered directly from a fire panel bell circuit?

Yes, the unit supports two trigger methods. Method 1 uses a separate 17-32V DC power supply with a switched negative trigger signal. Method 2 allows the unit to be powered and triggered directly from a standard fire panel bell circuit (2-core bell +/- circuit), which is particularly useful in installations where access to auxiliary power outputs is limited. When using Method 2, you must short out the GND/SW Neg connection terminals with a link wire. Note that when powered via the bell circuit, the isolation warning buzzer only operates when the bell circuit is active.

What is the anti-latch function and when should it be enabled?

The anti-latch feature (selectable via DIL switch 3) is designed to prevent system latch-up problems when resetting fire alarm systems. When enabled, the relay activates normally but automatically drops out after 5 seconds rather than maintaining a latched state. This is particularly useful when triggering latching fire zones or inputs on control panels, allowing the relay to provide a pulse trigger signal rather than a sustained contact closure, which can simplify system reset procedures and avoid potential reset complications.

How do I set the timer delay and what are the visual indicators?

To set the timer delay, ensure the unit is powered but not isolated and no trigger signal is present. If using bell input, temporarily remove any link across the SW neg terminals. Adjust the trimmer potentiometer on the PCB, turning it fully anticlockwise for no delay or clockwise to increase delay. The internal engineer LED (visible when cover is removed) flashes to indicate the delay setting: no flash equals timer off, 1 flash equals 1 minute, 2 flashes equals 2 minutes, and so on up to 5 flashes for 5 minutes. During countdown, the yellow front LED flashes rapidly and the unit produces a tick-tock sound.

What are the typical applications for the 500-200KS in fire alarm installations?

Common applications include delaying autodialler activation to allow alarm investigation before monitoring centres are alerted, temporarily isolating plant shutdown systems during periodic fire alarm testing to prevent unnecessary disruption to building services, controlling automatic fire door closure systems, managing roller shutter door operations on alarm activation, and interlinking satellite fire systems in shopping complexes or multi-building sites where auxiliary equipment coordination is required. The timer and isolation features make it particularly suitable for environments where false alarm management and system testing procedures need careful coordination.

What is the maximum contact rating and what types of loads can be switched?

The 500-200KS provides double pole changeover contacts with a maximum rating of 230V AC at 8A. The dual changeover configuration offers NO (normally open), COM (common), and NC (normally closed) contacts on both poles, providing flexibility for various switching applications. The relay is suitable for switching autodiallers, signalling equipment, door release mechanisms, and control circuits. When switching mains voltages, installations must comply with current IEE electrical wiring regulations. The relay contacts can handle both resistive and inductive loads typical of fire alarm auxiliary equipment.