Timers

Reference Material for Timers: Inrush Current

"---" indicates a constant current and therefore omitted from the table. All the values are approximate values and should therefore be used as a guide.

Timers

Time Switches

Note:The time of the inrush current is measured as shown in the following figure.

Timer Glossary

Term Definitions

ON Time

The period of time during which a required voltage is being applied to he operating circuit.

OFF Time

The period of time between the moment that resetting begins and the moment that the operating voltage is applied to the operating circuit.
Therefore, the OFF time of the Timer is larger than the resetting time.

Operating Time

The period of time from the application of a required voltage to the operating circuit until the completion of the time-limit contact operation.

Holding Time

The period of time from the completion of the time-limit operation to the start of the reset operation.

Resetting Time

The period of time from the interruption of the voltage supplied to the operating circuit during or after the time-limit operation until the return of the Timer to its initial state.

The resetting time of the Timer is the period of time during which all the internal components including the contacts, pointer, and the circuit components, such as the capacitor, of the Timer are reset.
If the Timer is in operation with an insufficient OFF time (i.e., the OFF time is less than the rated resetting time), the normal operation of the Timer cannot be expected. In such cases, the Timer may operate with insufficient operating time, operate instantaneously, or not operate at all. Be sure that the OFF time of the Timer is the same as or more than the rated resetting time.

Self-reset

To automatically reset the Timer by interrupting the voltage being supplied to the operating circuit.

Electrical Reset

To reset Timer by applying a required voltage to the reset circuit.

Manual Reset

To mechanically reset the Timer by manual operation.

Synchronous Motor (Time Switch)

A motor that operates in synchronization with the power frequency (50/60 ㎐). Because of the simplicity of a structure using this type of
motor, it is reasonably priced.
The motor stops when there is a power interruption, so the time must be reset after the power is restored.

Quartz Motor (Time Switch)

The motor is operated by quartz oscillation. The quartz motor is equipped with a corrective function for power interruptions, so it can be used immediately after the power is restored.

Accuracy of Operating Time

Differences of operating times measured when the Timer repeats operation under the same condition with a given setting time.
Formula for calculation (with operating time measured more than 5 times):

Accuracy of operating time

where,
T max.:
Maximum value of operating times measured at the same set time
T min.:
Minimum value of operating times measured at the same set time
TMs:
Maximum scale time (TMs is a set value in the case of a Digital Timer)

Differences in the operating time appear as a shift from the central value of the operation, so the maximum or minimum value is divided by 2 and expressed as a plus (+) or minus (-) indication.

If there are setting changes in the H3CA or other types of Analog Timer while they are in time-limit operation, the following operation will result.

T:
Final time-up time
T₁:
Time elapsed
T₂:
New setting
T₃:
Previous setting

Setting Error

A difference between the actual operating time and scale time.Formula for calculation (measurement position can be any scale position as long as it is set to 1/3 min. of the maximum scale time):

Setting error

where,
TM:
Average value of measured operating times
Ts:
Set time
TMs:
Maximum scale time (TMs is a set value in the case of the Digital Timer)

Influence of Voltage

A change in operating time when the voltage of the control power source changes within the permissible fluctuation range.
Formula for calculation:
Variation due to voltage change

where,
TM1:
Average value of operating times measured at rated voltage
TMx₂:
Average value of operating times measured at a voltage which causes the maximum deviation from TM1 within the permissible fluctuation range.
TMs:
Maximum scale time (TMs is a set value in the case of the Digital Timer.)

Influence of Temperature

A change in operating time when the ambient temperature changes within a permissible range.
Formula for calculation:
Variation due to temperature change

where,
TM₂:
Average value of operating times measured at 20°C.
TMx₂:
Average value of operating times measured at a temperature which causes the maximum deviation from TM2 within the specified ambient temperature range.
TMs:
Maximum scale time (TMs is a set value in the case of the Digital Timer.)

OFF Time Characteristics

A change in operating time when the operating time in a given OFF time and the OFF time are changed.
Formula for calculation:
OFF time characteristic

TM₃:
Average value of operating times measured with a 1-second OFF time.
TMx₃:
Average value of operating times measured with an OFF time that causes the maximum deviation from TMx₃ within the specified OFF-time range of one hour from the specified resetting time.
TMs:
Maximum scale time (TMs is a set value in the case of the Digital Timer.)

OFF-time characteristics are determined by the charging and discharging of a capacitor and resistor used in combination as an Electronic Timer. The haracteristics vary by ±1.5% to ±5%.

Operating time accuracy, setting error, influence of voltage, influence of temperature, and OFF-time characteristics are items used to express the precision of the Timer. Any of these items may be ignored depending on the particular specifications of the model.

The Motor Timer and Electronic Timer indicate these items by percentage values. The Count Timer indicates these items by differential time values because the differential range of the Timer's operating time is almost definite due to the operating principle of theTimer. Furthermore, the Count Timer total setting error can be indicated to express all these items in the case of the Count Timer.

Vibration Resistance (Malfunction)

The range of vibration during operation in which contacts that are closed will not open by vibration for a period exceeding the specified time (1 ms).

Vibration Resistance (Destruction)

The range of vibration in which there is no damage to parts during transport or use, and the operating characteristics are still satisfied.

Shock Resistance (Malfunction)

The range of shock during operation in which contacts that are closed will not open by shock for a period exceeding the specified time (1 ms).

Shock Resistance (Destruction)

The range of shock in which there is no damage to parts during transport or use, and the operating characteristics are still satisfied.

Insulation Resistance

The resistance offered by an insulating material to the flow of current resulting from an impressed DC voltage.

Dielectric Strength

The voltage level that will not cause insulation breakdown when applied for 1 minute to the same location as in the insulation resistance measurement.

Impulse Withstand Voltage (AC)

A voltage imposed between the operating power supply terminals or between a charged terminal and non-charged metal part to check the withstand surge voltage of the Timer. The impulse withstand voltage imposed between the operating power supply terminals is 3 kV and that imposed between a charged terminal and non-charged metal part is 4.5 kV with both using a ±1.2 × 50-μs standard waveform.

Noise Immunity

The mechanical and physical resistance of the Timer against external noise.
The noise resistance of the Timer is checked with a noise simulator, a coil load, an oscillating relay, and static electric noise.

Mechanical Life Expectancy

The life expectancy of a Timer when the control output of the Timer is operated under no load condition.

Electrical Life Expectancy

The life expectancy of a Timer when the control output of the Timer is operated to switch the specified voltage/current load connected to
the control output.
The electrical or mechanical life of the Timer is generally indicated by the operating times of control output. The electrical life is indicated by the operating time of the control output connected to a load and the mechanical life is indicated by the operating time of the control output with no load. The electrical life is shorter than the mechanical life.
The lighter the load is, the longer the electrical life will be. Therefore, to prolong the electrical life of the Timer, use the Timer to switch heavy loads via relays instead of directly switching them with the control output.

Symbols Used in Internal Connection Diagram of Timers