12

S8AS

Principle of Operation

The deterioration speed of the electrolytic capacitors varies

considerably with the ambient temperature. (Generally the speed

follows the Arrhenius Law, i.e., for every 10

°C increase in the

temperature, the rate of degradation doubles.) The S8AS monitors

the temperature inside the Power Supply, and calculates the amount

of deterioration according to the operating hours and internal

temperature.

Based on this amount of deterioration, the Power Supply will provide

an alarm indication and output when the period left for maintenance

reaches the set value.

Note: 1. Due to degradation of internal electronic parts, replace the

Power Supply approximately 15 years after purchase even

if the maintenance forecast monitor indication and output do

not appear.

2. The maintenance forecast is accelerated or decelerated

according to operating conditions. Periodically check the

display.

3. Acceleration or deceleration of the maintenance forecast

may cause the output to repeatedly go ON and OFF.

4. The accuracy of the maintenance forecast function may be

adversely affected by applications in which the AC input is

frequently turned ON and OFF.

Difference between Expected Life and Replacement Time

OMRON calculates the expected life based on the following

conditions.

1. Rated input voltage

2. Load rate: 50%

3. Ambient temperature: 40

°C

4. Standard Mounting

Note: The expected life is calculated by performing a temperature rise

test using an aluminum electrolytic capacitor, and therefore is

not a guaranteed value.

The expected life span of the S8AS is 10 years.

The maintenance forecast is the service life (the Power Supply's

internal temperature is monitored at all times) of the internal

electrolytic capacitors in actual operating conditions, and depends on

the customer's operating conditions. The maximum period of the

maintenance forecast is taken as 15 years.

Other Functions

* The sequencing functions are designed for the six branch outputs of one S8AS. There is no synchronization processing between S8AS Power

Supplies when more than one S8AS is used. Sequencing functions for branch outputs 7 and 8 are available only with the S8AS-48008N.

Function

Operation

Startup sequence

(Refer to Chart 5.)

The connection timing for branch outputs 1 to 6 and 8 can be set individually to offset the connection timing to the load

devices. Creating time delays between starting loads enables safer load operation. It also reduces total inrush current so

that power supply capacity can be optimized.

Setting range:

0.0 to 99.9 s in 0.1-s increments.

For the S8AS-24006N and S8AS-48008N, the settings are 0.0 s for branch output 1, 0.4 s for branch

output 2, 0.8 s for branch output 3, 1.2 s for branch output 4, 1.6 s for branch output 5, 2.0 for branch

output 6, 2.4 s for branch output 7, and 2.8 s for branch output 8. (Cannot be changed.)

*

Shutdown

sequence

(Refer to Chart 6.)

The cutoff timing for branch outputs 1 to 6 and 8 can be set individually to offset the cutoff timing of load devices for the

external tipping input or to enable an emergency stop.

Setting range: 0.0 to 99.0 s in 0.1-s increments. For the S8AS-24006N and S8AS-48008N, all branch outputs have a setting

of 0.0 s. (Cannot be changed.)

*

Startup Delay

A delay function is provided so that the abnormal current tripping function

or overcurrent alarm function will not be triggered by large initial inrush

currents, e.g., for capacitive loads or lamp loads. The abnormal current

tripping function will function once the set time has elapsed.

(Note: The delay is 40 ms and cannot be changed.)

t

Current

0

40 ms: Delay

Alarm function disabled

for large inrush

currents at startup.