Timers, Time Relays, Counters & Hour Meters
A Practical Guide for Every Industry
How the right timing device solves real problems — from factory floors to farms, from HVAC plants to food production. | Products available at pelek.uk | Principal Elektrik UK Ltd | 020 45 770 115
Most equipment failures, energy waste, and production inefficiencies have one thing in common: something happened at the wrong time. Timing devices — time relays, counters, and hour meters — are among the most cost-effective tools in electrical engineering. They prevent breakdowns, reduce energy consumption, extend equipment life, and replace manual processes that are easy to forget.
This guide is structured by industry. Whether you work in manufacturing, agriculture, building services, food production, or facilities management, you will find practical scenarios, real problems, and specific products that solve them — all available from pelek.uk, stocked and ready for fast UK delivery.
1. Understanding the Devices: A Quick Reference
A brief overview of each device type and what it does
Time Relays (Timer Relays)
A time relay introduces a controlled time delay into a circuit. When triggered — by power, a switch, or a signal — the relay waits for a set period before switching its output contacts. The four most common functions are:
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On-delay — output activates a set time after the input is energised. Example: start a ventilation fan 30 s after the machine starts.
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Off-delay — output stays active for a set time after the input is de-energised. Example: keep a cooling fan running 5 min after a motor stops.
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Repeat cycle (flasher) — output continuously switches on and off at set intervals. Example: pulse a dosing pump every 10 min.
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Single shot — output activates once for a set duration, then stays off until reset. Example: open a gate for 20 s per activation.
TENSE ON-Delay Time Relay ERV-08M DIN rail, 1 s – 100 h, 12–240V AC/DC
Source: pelek.uk/collections/timer-relays
TENSE On/Off-Delay Time Relay ERX-30 DIN rail, 0,1 s – 30 h, 12-230V AC/DC
Source: pelek.uk/collections/timer-relays
TENSE Asymmetric Cyclic Relay ERV-09D Repeat cycle, dual display
Source: pelek.uk/collections/timer-relays
Hour Meters
An hour meter records cumulative running time — like a car odometer but for time. It increments only while the equipment is powered, giving accurate operating hours rather than calendar time.
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Analogue SF-48 — panel-mount, rotating drum, up to 999,999 h, no power required for display. Ideal where simplicity and reliability are paramount. From £13.
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Digital HM-48 / HM-48D — LCD display, panel-mount, optional reset, 24V DC supply available. From £16.
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Digital DHM-DIN — DIN-rail, LCD, resettable, 230V AC. From £28.
TENSE Digital Hour Meter DHM-DIN DIN rail, LCD, up to 99,999 h, resettable, 230V AC
Source: pelek.uk/products/digital-hour-meter-up-to-99999-hours-150v-260vac
Impulse Counters
An impulse counter counts electrical pulses from sensors, switches, or encoders. When the count reaches a preset value, an output relay can trigger an alarm, stop a machine, or start the next process step. TENSE DS-48 and DS-72A models feature up/down counting to 7,500 Hz, EEPROM memory (count retained after power loss), and relay + SSR outputs.
Device at a Glance
| Device |
What It Measures |
Key Output |
Typical Price |
| On-delay time relay |
Time elapsed after energising |
Relay contact (on after delay) |
£15–£25 |
| Off-delay time relay |
Time elapsed after de-energising |
Relay contact (off after delay) |
£15–£25 |
| Repeat cycle relay |
Periodic intervals |
Cyclic relay switching |
£20–£30 |
| Analogue hour meter SF-48 |
Cumulative running hours |
Visual display only |
£13 |
| Digital hour meter HM-48 |
Cumulative running hours |
Visual display, optional reset |
£16 |
| Digital hour meter DHM-DIN |
Cumulative running hours |
DIN rail, resettable |
£28 |
| Impulse counter DS-48 |
Pulse count (up/down) |
Relay + SSR output |
£55 |
| Impulse counter DS-72A |
Pulse count (up/down) |
Relay + SSR, larger display |
£65 |
2. Manufacturing & Production
Timing control for machines, conveyors, presses, and production lines
Manufacturing environments demand timing devices that are robust, reliable, and easy to set. DIN-rail mounted relays fit neatly inside existing control panels. Hour meters give maintenance teams the data they need without expensive SCADA systems. Impulse counters replace manual tally systems with automatic batch control.
Product Image — TENSE Timer Relay DIN rail, manufacturing control panel applicationSource: pelek.uk/collections/timer-relays
2.1 Conveyor Belt Sequencing — On-Delay Relay
Problem
Starting three conveyor belts simultaneously causes supply overcurrent and material pile-up at transfer points.
Solution
Three on-delay time relays staggered by 5 seconds each. Belt 1 starts immediately, Belt 2 after 5 s, Belt 3 after 10 s — all triggered by the same start signal.
2.2 Injection Moulding — Clamping Dwell Timer
Problem
Manual timing of mould dwell periods is inconsistent, leading to reject rates and variable cycle times.
Solution
A single-shot time relay, triggered by the injection completion signal, holds the clamp solenoid energised for the exact dwell period. When the timer expires, it releases the clamp automatically.
2.3 Batch Production Counting — Impulse Counter
Problem
Manual counting of batch quantities leads to overfill, underfill, and wasted operator time at the end of each production run.
Solution
A proximity sensor detects each item. The DS-48 impulse counter counts up to the preset batch quantity then closes its output relay to stop the conveyor, sound an alarm, or trigger the next process step.
2.4 Machine Service Scheduling — Hour Meter
Problem
Maintenance intervals based on calendar time lead to over-servicing of lightly-used machines and under-servicing of heavily-used ones.
Solution
Fit a panel-mount hour meter to each machine. Service intervals are triggered by actual running hours. A machine at 500 hours gets serviced; one at 120 hours does not.
💡 Pro tip: In multi-machine facilities, fit an hour meter to every motor. Over 6–12 months, the data reveals which machines work hardest and which sit idle — invaluable for capacity planning and capex decisions.
2.5 Pneumatic Press — Off-Delay Cooling Timer
Problem
Rapid cycling of a hydraulic press overheats the oil, degrading seals and reducing clamping force consistency.
Solution
An off-delay relay locks out the next cycle for a set cooling period. The operator cannot initiate another cycle until the relay times out and releases the interlock.
3. Agriculture & Horticulture
Irrigation, livestock systems, grain drying, and rural machinery
Agricultural operations often run unattended for hours. Timing devices replace the need for constant human supervision — watering cycles run automatically, pumps stop before they run dry, and equipment logs its own working hours.
TENSE Repeat Cycle Relay DFR-72 DIN rail, irrigation and agricultural automation
Source: pelek.uk/collections/timer-relays
3.1 Irrigation Scheduling — Repeat Cycle Relay
Problem
Manual irrigation control wastes water and causes inconsistent crop yields due to irregular watering intervals.
Solution
A repeat cycle relay runs the irrigation pump for a set ON period (e.g. 20 min), then keeps it off for a set OFF period (e.g. 4 hours), cycling continuously during the growing day.
🔧 A market garden with 4 irrigation zones uses four repeat cycle relays set to different intervals — leafy crops every 3 hours, root vegetables every 6 hours, polytunnel tomatoes every 2 hours. No PLC required; total cost under £100.
3.2 Pump Protection — Hour Meter for Service Tracking
Problem
Pump service intervals are missed because hours of use are not tracked, leading to expensive in-season failures.
Solution
Fit a digital hour meter to the pump control panel, wired to the pump motor supply. Service is scheduled every 1,000 hours of actual pumping time.
3.3 Grain Drying — Staged Fan Control with On-Delay
Problem
Simultaneous start of heater and fan scorches grain near the air inlet; simultaneous stop traps heat in the bulk, risking hot spots and spoilage.
Solution
An on-delay relay starts the heater 30 s after the fan, ensuring full airflow before heat is applied. An off-delay relay keeps the fan running 5 min after the heater is switched off.
3.4 Livestock Feeding Systems — Interval Counter
Problem
Manual feed delivery records are inconsistent and do not detect auger jams or blocked hoppers until animals show signs of under-feeding.
Solution
A limit switch on the auger motor feeds pulses to the DS-48 counter. If the daily target count is not reached by a set time, an alarm output is triggered.
3.5 Tractor & Agricultural Machinery — Hour Meter
Problem
Agricultural machinery is serviced on calendar time rather than engine hours, leading to missed oil changes and filter replacements on heavily-worked machines.
Solution
A panel-mount analogue hour meter, wired to the ignition supply, records engine hours continuously. Simple, robust, and requires no battery.
✅ At just £13, the SF-48 pays for itself the first time it prevents a missed engine oil change on a £50,000 tractor. Fit one to every piece of powered farm equipment.
4. HVAC & Building Services
Ventilation, heating, cooling, and building automation
HVAC systems run for thousands of hours a year, often unattended. Timing devices prevent nuisance trips, energy waste, and premature equipment failure. From a simple stairwell light delay to complex air handling unit sequencing, time relays provide a reliable, low-cost alternative to full BMS integration for smaller installations.
Product Image — TENSE DIN Rail Timer Relay DRV-10 HVAC panel applications
Source: pelek.uk/collections/timer-relays
4.1 Extract Fan Run-On — Off-Delay Relay
Problem
Kitchen extract fans stop when the cooking equipment is switched off, leaving steam, grease vapour, and residual heat in the canopy and ductwork.
Solution
An off-delay relay keeps the extract fan running for 10 min after the cooking equipment is de-energised. The delay is adjustable to suit kitchen size and duct run. No BMS required.
4.2 Stairwell & Corridor Lighting — Single-Shot Relay
Problem
Corridor lights stay on all night because the manual switch is left on, wasting energy and increasing lamp replacement costs.
Solution
A single-shot time relay, triggered by a PIR motion sensor, energises the lighting for a set period (e.g. 3 min) then switches it off automatically, regardless of switch state.
4.3 Air Handling Unit — Staged Start Sequencing
Problem
Simultaneous start of AHU fans and heating battery trips the MCB and risks fan motor damage from running against a closed damper.
Solution
A cascade of on-delay relays: damper opens first → Fan 1 after 30 s → Fan 2 after 45 s → heating battery after 60 s.
4.4 Boiler & Heat Pump — Running Hours Monitoring
Problem
Boiler service intervals are missed or duplicated because running hours are not recorded, risking efficiency loss, warranty invalidation, and safety incidents.
Solution
A DIN-rail hour meter wired to the burner control circuit records actual firing hours. The facilities manager reads the meter monthly and schedules service based on real hours, not guesswork.
4.5 Cooling Tower — Bleed-Off Dosing Timer
Problem
Manual chemical dosing of cooling tower water is inconsistent, leading to scale buildup, biological growth, and Legionella risk.
Solution
A repeat cycle relay triggers the dosing pump for 2 min every 2 hours. An hour meter on the dosing pump tracks chemical usage for compliance records.
💡 Legionella control records are a legal requirement under ACoP L8. An hour meter on the dosing pump provides verifiable evidence that the dosing schedule was followed — far simpler than manual log books.
5. Food & Beverage Production
Process control, hygiene intervals, batch counting, and CIP systems
Food production environments have two non-negotiable requirements: consistency and hygiene. Timing devices deliver both — automating the intervals and sequences that define product quality, while logging the evidence that auditors and certifiers require.
Product Image — TENSE Multifunction Time Relay DIN rail, food process sequencing and CIP control
Source: pelek.uk/collections/timer-relays
5.1 Clean-In-Place (CIP) — Multi-Stage Timer Sequence
Problem
CIP stages are manually timed by operators using stopwatches, leading to inconsistent cleaning and occasional regulatory non-compliance.
Solution
A cascade of time relays sequences each CIP stage automatically: pre-rinse (5 min) → caustic wash (20 min) → intermediate rinse (5 min) → acid (15 min) → final rinse (10 min). Each relay triggers the next at the end of its period.
5.2 Filling Line — Batch Counter with Reject Output
Problem
Manual batch recording on a busy filling line is inaccurate. Over- and under-fills go undetected until QC checks, causing waste and rework.
Solution
A photoelectric sensor detects each bottle. The DS-72A counter counts up to the target batch quantity then closes its relay to stop the conveyor and trigger an operator alert. Reset for the next batch at the touch of a button.
5.3 Dough Mixer — Mixing Cycle Timer
Problem
Inconsistent mixer timing produces variable dough quality, affecting bake performance and product consistency across batches.
Solution
A single-shot relay, triggered by the mixer start button, runs the mixer for the exact programmed period then stops it automatically. The operator loads ingredients and presses start — the timer does the rest.
5.4 Refrigeration Compressor — Running Hours for Compliance
Problem
Refrigeration compressors are serviced on calendar dates, but summer operation means the compressor runs far more hours than in winter, with under-servicing going undetected.
Solution
A digital hour meter wired to the compressor motor records actual running hours. Service is scheduled every 2,000 hours regardless of season. The reset function allows the meter to be zeroed after each service.
6. Water & Wastewater Treatment
Pump control, dosing, aeration, and process sequencing
Water treatment relies on precision timing. Whether it is the interval between dosing cycles, the duration of a backwash, or the rotation schedule for duty/standby pumps, timing devices provide reliable, low-cost automation for systems that must run continuously.
Product Image — TENSE Digital Hour Meter DHM-DIN DIN rail, pump & water treatment monitoring
Source: pelek.uk/products/digital-hour-meter-up-to-99999-hours-150v-260vac
6.1 Duty/Standby Pump Alternation — Repeat Cycle Relay
Problem
The duty pump fails after 5,000 hours while the standby pump's mechanical seal has dried out from 5 years of idleness. Both require replacement simultaneously.
Solution
A repeat cycle relay alternates duty and standby pumps on a defined schedule — e.g. switching every 24 or 168 hours. Both pumps accumulate equal running hours and remain mechanically exercised.
6.2 Chemical Dosing — Interval Timer
Problem
Manual chemical dosing results in wildly variable water chemistry between operator visits, risking regulatory non-compliance.
Solution
A repeat cycle relay drives the dosing pump for a set ON period at every defined interval. ON and OFF periods are independently adjustable to tune the dose rate. An hour meter provides a verifiable dosing record.
6.3 Filter Backwash — Timed Sequence Controller
Problem
Filter backwash is triggered manually when operators remember, resulting in inconsistent filter performance and occasional clogging.
Solution
Relay 1 opens the drain valve. After 30 s, Relay 2 starts the backwash pump. After 10 min, both outputs reset and the filter returns to service. A repeat cycle relay triggers the whole sequence every 24 hours.
6.4 Pump Running Hours — Compliance Logging
Problem
An abstraction licence requires records of pump operating hours to demonstrate compliance, but no logging system is in place.
Solution
A DIN-rail digital hour meter wired to the pump motor starter auxiliary contacts records accumulated hours continuously. Monthly meter readings provide the required compliance log at a fraction of the cost of a data logger.
7. Facilities Management & General Industry
Asset tracking, energy management, and maintenance planning
Facilities managers are responsible for keeping equipment running across large, diverse estates. Timing devices provide the visibility and automation needed to manage assets proactively rather than reactively.
7.1 Generator Testing — Automatic Exercise Timer
Problem
The standby generator fails to start during a power cut because it has not been exercised for 6 weeks, the battery is flat, and the diesel has gelled.
Solution
A weekly repeat cycle relay (168-hour intervals) automatically starts the generator for a 30-min exercise run at the same time each week. An hour meter logs total engine hours for service scheduling.
7.2 Compressed Air System — Compressor Running Hours
Problem
The facilities team suspects significant air leaks but cannot quantify the problem without expensive flow measurement equipment.
Solution
Hour meters fitted to each compressor motor reveal that one 22 kW compressor is running 20 h/day where only 10 h should be needed. The excess 10 hours quantifies the leakage — justifying a leak detection survey.
🔧 A facility installs SF-48 hour meters on 4 compressors (total cost: £52). Within 3 months, data reveals Compressor 3 runs 40% more hours than the others — a leak is found and repaired, saving an estimated £3,200/year in electricity.
7.3 Car Park & External Lighting — Timed Override
Problem
Security staff switch on external lights for a delivery and forget to switch them off, leaving the entire car park lit all day.
Solution
Pressing the override button energises the lights and starts the timer. After the set period (e.g. 2 hours), the relay drops out and returns control to the photocell. The override cannot be left on indefinitely.
7.4 Lift & Escalator Maintenance Tracking — Hour Meter
Problem
Lift maintenance is triggered by calendar month regardless of usage, resulting in over-servicing of low-traffic lifts and under-servicing of high-traffic ones.
Solution
A digital hour meter wired to the lift motor contactor auxiliary circuit records actual drive motor operating hours. Maintenance is called when the meter reaches the contract trigger value, irrespective of the calendar.
8. Renewable Energy & Power Systems
Solar, wind, battery storage, and backup power applications
Renewable energy systems and backup power installations often run unattended in remote locations. Timing and counting devices provide low-cost monitoring and automation without the need for complex SCADA or cloud-connected systems.
8.1 Battery Charge Equalisation — Repeat Cycle Timer
Problem
Battery bank capacity degrades faster than expected because cells are never equalised, with some chronically undercharged and others overcharged.
Solution
A repeat cycle relay triggers the equalisation charger for a set period every defined interval (e.g. 2 hours every 30 days), providing a fully automatic schedule without manual intervention.
8.2 Solar Inverter & Generator — Running Hours Log
Problem
The diesel backup generator for an off-grid solar installation has unknown running hours — service intervals are estimated, fuel consumption is unverified, and carbon reporting is inaccurate.
Solution
An hour meter wired to the generator starter circuit records every hour of engine operation. Monthly readings provide verified run-time data for fuel budget, service planning, and emissions reporting.
8.3 Wind Turbine — Revolution Counting with Impulse Counter
Problem
A small wind turbine installation has no production data — the owner cannot verify energy output, detect performance degradation, or support a warranty claim.
Solution
A proximity sensor generates one pulse per rotor revolution. The DS-48 counter accumulates the total revolution count, which can be read and logged periodically to estimate energy production.
9. Choosing the Right Device: A Selection Guide
Not sure which device fits your application? Use this decision guide
1 What do you need to do?
| If you need to… |
Choose… |
| Delay the start of something after a trigger |
On-delay time relay |
| Keep something running after its trigger is removed |
Off-delay time relay |
| Switch something on and off repeatedly at intervals |
Repeat cycle time relay |
| Activate something once for a fixed duration |
Single-shot time relay |
| Count items, events, or pulses |
Impulse counter (DS-48 or DS-72A) |
| Record total running hours of a machine |
Hour meter (SF-48, HM-48, or DHM-DIN) |
| Track hours AND reset after service |
Digital hour meter with reset (HM-48D or DHM-DIN) |
| Log hours on a 24V DC or battery system |
HM-48D (accepts 24V AC/DC supply) |
2 What timing range do you need?
| Timing Range |
Suitable Relay |
Notes |
| 0.1 s – 30 s |
ERV-30 on-delay (TENSE) |
Machine sequencing, valve travel |
| 0.1 s – 6 s |
ERX-30 off-delay (TENSE) |
Short run-on, hydraulic cool-down |
| Seconds to minutes |
TENSE multifunction relay |
Adjustable via front-panel pot |
| Minutes to hours |
TENSE multifunction relay |
Wider range models available |
| Fixed interval cycling |
TENSE repeat cycle relay |
ON and OFF periods independently adjustable |
3 How many hours does the equipment run?
| Equipment Usage |
Recommended Hour Meter |
Price |
| Low-use (up to 10 h/day) |
SF-48 analogue, panel mount |
£13 |
| General use (up to 99,999 h) |
HM-48 digital, panel mount |
£16 |
| High-use with service resets |
HM-48D digital with reset |
£16 |
| DIN rail installation |
DHM-DIN digital with reset |
£28 |
| 24V DC / battery systems |
HM-48D (24V AC/DC input) |
£16 |
10. Conclusion: Small Devices, Big Returns
A timing or counting device costing £13–£65 routinely prevents problems worth many times more
The applications in this guide share a common theme: a simple, inexpensive device prevents a problem that would cost far more to fix — a pump breakdown, a compliance failure, a quality reject, a wasted maintenance visit, or a runaway energy bill.
These devices require no programming, network connectivity, or specialist commissioning. A competent electrician can wire a DIN-rail time relay in under 30 minutes. An hour meter takes even less time. Yet the operational visibility and automation they provide are transformative.
✅ Start with the problem you know you have. Machine serviced on guesswork? Fit an hour meter — £13 to £28. Something starting before it should? Add an on-delay relay — £18. A pump running at the wrong times? Add a repeat cycle relay — £20. The return on investment is typically measured in weeks, not years.
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This article is an independent practical guide. Product information is based on listings current at pelek.uk at time of writing. Prices and availability are subject to change.
