What Is a Flasher Timer Relay? Types and Selection Criteria
A flasher timer relay is a timer relay that energises and releases its output contact in turn for set working (ON) and pause (OFF) times until the supply is removed.
A flasher timer relay is a timer relay that, as long as it is powered, energises its output contact for the set working (ON) time, releases it for the set pause (OFF) time and repeats this cycle on its own. In panels it is used to flash warning lamps or to run loads such as fans and pumps at intervals; it is not the same product as an automotive flasher relay.
Types
- Asymmetric (dual setting): ON and OFF times are set separately. Most models in the catalog are of this type.
- Symmetric: ON and OFF times are equal; an asymmetric relay can run symmetrically by setting both times to the same value.
- Fixed pulse: ON time is fixed and only OFF time is adjustable (Entes EF-10).
- Function-selectable digital: Flasher or on-delay function is selected (Tense ERD-48K).
Catalog models compared
| Model | ON / OFF setting | First phase | Supply | Output | Housing |
|---|---|---|---|---|---|
| Tense ERF-09 | 1 s–100 h, set separately | ON | 160–260 V AC | 5 A 250 V AC, resistive | Classic DIN housing, rail |
| Tense ERV-09 | 1 s–100 h, set separately | ON | 160–260 V AC or 24 V AC/DC | 5 A 250 V AC, resistive | Rail |
| Tense ERV-09D | 0.1 s–99 min, dual digital display | ON | 100–240 V AC or 12 V DC | 5 A 250 V AC, resistive | V-Otomat DIN II housing, rail |
| Tense ERP-2F | 0.1–60 min, set separately | Not specified | Not specified | Not specified | 48 × 48 mm panel |
| Tense DFR-72 | 1 s–99 min, separate s/min ranges | ON | 150–270 V AC | 5 A 250 V AC, resistive | 72 × 72 mm panel |
| Tense ERD-48K | 99.9 s / 999 s / 99.9 min / 999 min scale | Not specified | 100–240 V AC | Delayed NO+NC and instant NO, 2 A resistive | 48 × 48 mm panel |
| Entes EF-10 | ON 0.5 s fixed, OFF 1–10 s | ON | 230 V AC | 1 C/O, 8 A, 2000 VA (cosφ=1) | PK 22, rail |
| Schneider Electric RE22R1MLMR | 0.05 s–300 h | L: OFF, Li: ON | 24–240 V AC/DC | 1 C/O, 8 A | 22.5 mm modular, rail |
| Schneider Electric RE48ACV12MW | 0.02 s–300 h | L: OFF, Li: ON | 24–240 V AC/DC | 2 C/O, 5 A | 48 × 48 mm, 11-pin socket |
Values are taken from the manufacturers' datasheets.
Selection criteria
- ON and OFF setting: Asymmetric if both times must change; fixed pulse if you only need a short pulse with an adjustable gap.
- Time range: The longest time you need must fall within the model's upper limit.
- First phase: If the load must wait through a pause before it runs, rather than starting as soon as power arrives, you need the pause-first (L) function.
- Supply: The relay's supply input must match the control circuit voltage.
- Output and load: The contact ratings in the Tense and Entes datasheets are for resistive loads; switch motors, pumps or LED drivers through a contactor. If two circuits must follow the same cycle, RE48ACV12MW with two timed contacts fits.
Common mistakes
- Connecting an inductive load directly to the relay contact: Entes states that without a contactor the contacts may stick.
- Changing the range while powered: On ERV-09D a new range takes effect only after the supply is switched off and on again.
- Reversing the DC supply: On ERV-09D the AC supply goes to A1-A2 and 12 V DC to A2 (-) and A3 (+).
- Setting a long time directly on a high range: Tense recommends setting the time on a low range with a stopwatch and then raising the range: hitting 7.5 seconds on the 10-second range and switching to the 10-hour range gives 7.5 hours.
- Leaving X2 unconnected on RE22R1MLMR: On this model the Li function, which starts with ON, works only while input X2 is permanently energised.
Related standard
- IEC 61812-1: Time relays for industrial and residential use; setting and repeat accuracy in Schneider Electric datasheets are stated to this standard.
Brands in the catalog
The Flasher Timer Relays category has 9 active products: Tense 6 (ERF-09, ERV-09, ERV-09D, ERP-2F, DFR-72, ERD-48K), Schneider Electric 2 (RE22R1MLMR, RE48ACV12MW), Entes 1 (EF-10). Devices that offer flashing alongside other functions are in the Multi-Function Timer Relays category (confirm the flasher function in the datasheet). If you only need a flashing warning, stack lights and warning lights with a built-in flasher need no separate relay.
Frequently asked questions
What is the difference between a symmetric and an asymmetric flasher relay?
In a symmetric flasher the ON and OFF times are equal. In an asymmetric flasher the two times are set separately; for example a pump can run for 5 minutes and rest for 30 minutes.
Does a flasher relay start the cycle with ON or with OFF?
It depends on the model. Tense ERF-09, ERV-09, ERV-09D, DFR-72 and Entes EF-10 start with ON. On Schneider Electric RE22R1MLMR and RE48ACV12MW you select function L, which starts with the pause, or Li, which starts with ON.
Can a flasher relay run a motor or pump directly?
It is not recommended. The contact ratings in the Tense and Entes datasheets are for resistive loads; with motors and pumps the relay should drive a contactor coil.
Is there a flasher relay for 12 V or 24 V DC?
Yes. Tense ERV-09D has a 12 V DC input and Tense ERV-09 a 24 V AC/DC input; Schneider Electric RE22R1MLMR and RE48ACV12MW run on 24–240 V AC/DC.