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Safety Precautions for All Timers

Refer to the Safety Precautions for individual Timers for precautions specific to each Timer.

The following Timers contain lithium batteries that are not explosion proof.

Timers with Replaceable Batteries: Y92S-20 (for H5CN-M)
The battery may occasionally rupture, ignite, or leak fluid. Do not short the positive and negative terminals. Do not charge, disassemble, deform under pressure, or throw the battery into a fire. If a non-specified battery is used, the battery may leak fluid or rupture, occasionally resulting in equipment failure or minor injury. Use only the specified battery.

The following Timers contain lithium batteries that are explosion proof.

Timers with Built-in Batteries: H5AN-4DM, H5S, H5F, H4KV, and H5L

The Timer contains a lithium battery, which may occasionally ignite or rupture. Do not disassemble, deform under pressure, heat to 100°C or higher, or incinerate the Timer.

Precautions for Safe Use

Operating Environment

Use the Timer within the ratings specified for ambient operating temperature and ambient operating humidity for each model.

Store the Timer with the specified temperature range for each model. If the Timer has been stored at a temperature of less than -10°C, allow the Timer to stand at room temperature for at least 3 hours before using it.

Use the Timer within the performance specified for water and oil exposure for each model.

Do not use the Timer in locations subject to shock and vibration. Long-term usage in such locations may damage the Timer due to stress.
Magnetic contactors generate a shock of 1,000 to 2,000 m/s2 when switching a load. When mounting to DIN Track, separate magnetic contactors from the Timer so that the Timer is not subjected to vibration and shock. Use anti-vibration rubber.

Do not use the Timer in locations subject to excessive dust, corrosive gases, or direct sunlight.

Do not use organic solvents (such as paint thinner or benzine),strong alkalis, or strong acids because they will damage the external finish of the Timer.

Separate the input devices, input wiring, and Timer as far as possible from sources of noise and power lines carrying noise.

When using the Timer in environments subject to large amounts of static electricity (e.g., pipes carrying molding materials, powders, or fluid materials), separate the Timer as far as possible from the sources of static electricity.

Do not remove the external case from the Timer.

Do not use the Timer in locations where condensation may occur due to high humidity or sudden temperature changes.
Condensation inside the Timer may result in malfunction or damage to Timer elements.

The life of internal parts may be reduced if Timers are mounted in close proximity to each other.

Resin and rubber parts (e.g., rubber packing) may deteriorate,shrink, or harden depending on the operating environment (e.g.,subjected to corrosive gases, ultraviolet light, or high temperatures). We recommend periodic inspection and replacement.

Normal operation may not be possible in locations subject to sulfidizing gas, such as in sewer systems or waste incinerators. OMRON does not market any Timers or other control devices for operation in atmospheres containing sulfidizing gas. Seal the Timer so that sulfidizing gas will not enter it. If sealing is not possible, OMRON does provide special Timers with improved resistance to sulfidizing gas. Ask your OMRON representative for details.

Power Supply

Be sure that the voltage applied is within the specified range,otherwise the internal elements of the Timer may be damaged.

Install a switch or circuit breaker that allows the operator to immediately turn OFF the power, and label it to clearly indicate its function.

Maintain voltage fluctuations in the power supply within the specified range.

Use a commercial power supply for the power supply voltage input to models with AC inputs.
Inverters with an output frequency of 50/60 Hz are available, but the rise in the internal temperature of the Timer may result in ignition or burning. Do not use an inverter output for the power supply of the Timer.

The Timers listed below cannot be directly turned ON and OFF by using an AC 2-wire proximity sensor to turn the Timer's power supply ON and OFF.
Use the following countermeasure when using an AC 2-wire proximity sensor with the Timer. (The power supply circuit in the Timer uses half-wave rectification. Only a half AC wave is supplied to the proximity sensor, which may cause operation to be unstable.)

Applicable Models

H3Y, H3YN, H3RN, H3CA-8, RD2P, and H3CR(-A, -A8, -AP, -F, and-G)


Wire through a relay and use the relay contacts to turn the power supply ON and OFF.
Confirm the stability of operation after making the connections.

Install protective measures (such as earth leakage breakers, wiring breakers, or fuses) on the power supply side according to any applicable laws or regulations.

Correctly Handling Input Signals

Malfunction due to noise may occur if input wiring is placed in the same duct or conduit as power lines or high-voltage lines. Separate input wiring from power lines and wire them in a separate system.Also, use shielded cables, use metal conduits, and keep wiring distances as short as possible.

Timers with Relays

Do not connect a load that exceeds contact ratings, such as the switching capacity (contact voltage or contact current). Insulation faults, contact welding, contact faults, and other failures to achieve specified performance may occur and the relay may be damaged or may burn.

Continued use with deteriorated performance may ultimately result in insulation breakdown between circuits or relay burning. The life of the built-in relay is greatly affected by switching conditions.Before using the Timer, test operation under actual application conditions and confirm that the switching frequency presents no problems in performance.

Electrical life depends on the type of load, switching frequency, and ambient environment. Observe the following precautions when using the Timer. When switching a DC load, contact transfer may cause the contacts to stick or may cause contact failure. Confirm applicability and consider using a surge absorbing element. When switching at high frequencies, heat generated by arcing may cause contacts to melt or may cause metal corrosion. Consider connecting an arc absorbing element,reducing the switching frequency, or lowering the humidity.

The surge current depends on the type of load, which also affects contact switching frequency and the number of operations. Check the rated current and the surge current, and design the circuits with sufficient margin.

Resistive loadSolenoid loadMotor loadIncandescentlamp load
Rated current10 to 20 times the rated current5 to 10 times the rated current10 to 20 times the rated current
Sodium lightloadsCapacitorloadsTransformerloadsMercury lightloads
1 to 3 times the rated load20 to 40 times the rated load5 to 15 times the rated load1 to 3 times the rated load

Arcing when switching and relay heating may result in ignition or explosion. Do not use the Timer in atmospheres subject to inflammable or explosive gases.

Contact faults may occur. Do not use the Timer in atmospheres subject to sulfidizing gas, chloride gas, or silicon gas.

The switching capacity for DC voltage loads is lower than that for AC voltage loads.

Timers with Non-contact Outputs

Short faults or open faults may occur due to destruction of the output element. Do not use the Timer for a load that exceeds the rated output current.

Short faults or open faults may occur due to destruction of the output element from reverse electromotive force. When using the Timer for a DC inductive load, always connect a diode as a countermeasure against reverse electromotive force.

Other Precautions

Confirm that you have the correct model before using it.

Be sure that all terminals are wired correctly.

Always test the output status with a tester before using a Timer with a built-in keep relay (e.g., the H3CR-H and H3DE-H). Shock resulting from dropping the Timer during transport or handling may cause the output contacts to reverse or to be in a neutral status.

Leaving the Timer with outputs ON at a high temperature for a long time may hasten the degradation of internal parts (such as electrolytic capacitors). Use the Timer in combination with relays and avoid leaving the Timer with the output turned ON for an extended period of time (e.g., for more than a month). Reference Example (Use the Timer as shown below.)

Be sure that only a qualified worker (e.g., an electrical engineer) performs electrical work for the Timer.