Formation of the Standards Key Points.
Instructions on how to gather the necessary data and apply the format are contained in the Standard
Evaluate the voltage sag environment of the power supply system.
Evaluate the voltage sag susceptibility of process equipment.
Overlay of sag environment and equipment susceptibilities.
Determine the cost of a process disruption and how to evaluate pay back.
Investment Return
------------------------------ ----------------------------------
One-time capital $_______ Annual benefit $_______
outlay
+ -
One-time operating $_______ Ongoing annual $_______
expenses expense
------------------------------ ------------------------------------
Net Investment $_______ Net annual return $_______
Pay back = (net investment / net annual return) * 12 = ____ Months
Example data entered in the compatibility impact financial analysis form. An alternative is to improve the power supply to the photo eye and use a ridethrough device on the relay. The improved photoeye supply cost $82 and the ridethrough device for the (7)relays is $28 . These devices will make the ridethrough of the photoeye and the relays comparable to the PLC. Of the projected 18 sag events per year that occurred during production hours, six of them, based on past performance, are interruptions greater than 30 seconds in duration. The ride through device will not protect the plant for these events. Therefore, on average, these devices are projected to save the plant from 12 disruptions at $14,300 each or $171,600 per year.
Cost estimate for implimenting photoeye and relay solution:
Testing to find offending photoeye and relay: $4000/day * 2 days = 8000
Engineering of Modifications: $95/hr * 10 hours = $950
Materials: ($82 pwr supply + (7*$28 /relay)+ Misc $140) = $418
Installation labor (2 techs 4hrs): $78/hr * 8 hours = $624
TOTAL $9,992
Scheduled downtime for Testing and Modifications:
$6200/hr * 6 hours = $37,200
This information is entered in the financial analysis form and is shown . The simple payback is just under 1/3 month which is sufficiently favorable that a more detailed financial analysis may not be required.
Investment Return
------------------------------ ----------------------------------
One-time capital $9,992 Annual benefit $171,600
outlay
+ -
One-time operating $37,200 Ongoing annual $0
expenses expense
------------------------------ ------------------------------------
Net Investment $47,192 Net annual return $171,600
Pay back = 0.27 months = ( $47,192 / $171,600 ) * 12
SEE THE DRAFT STANDARD FOR FURTHER EXPLANTION .....
Comments to Larry Morgan