User's Manual Part 1

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The GS820 System

2.11

Four Point Lift

The following functions are available for applications

such as container cranes and gantry cranes that

require load indication from four load sensors

simultaneously.

• Sum load indication

• Imbalance

• Slack Rope

These functions can be used to generate an alarm

condition on the lockout wires of the GS820.

2.11a Sum Load Indication

When sum load indication is programmed the sum

of the loads on the pre-determined load sensors is

indicated by the operation display. To activate sum

load indication program a “Sum load sensor” in the

sensor list. The “ID number” is used to identify the

load sensors to be summed.

Sum maximum limit. The maximum limit for

the sum load can be adjusted in the limit menu;

the default maximum limit for sum load

indication is 10000 (lb or kg depending on load

display units).

Program sum load indication

1. Go to menu 4) INSTALLATION and select 4A1)

SENSOR LIST.

2. Enter the user password and press Enter.

3. Use Up and Down to advance to the next

available sensor position, usually following the

four load sensors and press Enter to modify.

4. Determine the sum load cell “ID number”. For

example: ID 1234 to indicate the sum of load

sensors № 1, № 2, № 3, and № 4, or ID 34 to

indicate the sum of load sensors № 3 and № 4.

5. Use Up and Down to select the sensor type

“Sum load cell” and press Enter to confirm.

6. Use Up and Down to adjust the ID number and

press Enter.

7. Press Enter.

8. Use Up and Down to advance to the next

available sensor position to program the

imbalance sensor or press Exit to return to the

operation display.

9. Adjust the sum maximum limit in menu 6)

YSTEM LIMITS.

2.11b Imbalance

Systems programmed for four load sensors and four

load sum indication can be programmed with an

imbalance sensor to warn against uneven load

distribution or against unwanted rope payout if one

corner of the load touches down before the others.

Imbalance factor limit. The imbalance factor

is the percent difference between the load on

one load sensor and the average load on the

other three. The imbalance factor is calculated

for each of the four load sensors and then

compared to an adjustable limit. The default

imbalance factor limit is 15%.

Imbalance minimum limit. Imbalance is not

calculated when the four load sum is below the

imbalance minimum limit. Adjust this limit to

avoid generating an imbalance alarm under

minimum load conditions (for example: with an

empty container or with rigging only). The

default imbalance minimum limit is 1000

(pounds or kilograms depending on load

display units).

Examples:

Program the imbalance sensor

1. Go to menu 4) INSTALLATION and select 4A1)

SENSOR LIST.

2. Enter the user password and press Enter.

3. Use Up and Down to advance to the next

available sensor position, usually following the

Imbalance factor calculation for load sensor № 1

A = Load № 1 B = Load № 2

C = Load № 3 D = Load № 4

Load № 1 (A) Imbalance Factor = 100 x

(Average B,C,D) - A

(Average B,C,D)

If the imbalance factor limit is 15%, then the system is safe.

A = 7500 B = 8100

C = 8000 D = 8200

Load № 1 (A) Imbalance Factor = 100 x = 7.5 %

8100 - 7500

8100

If the imbalance factor limit is 15%, then an imbalance alarm

is generated.

A = 6800 B = 8100

C = 8000 D = 8200

Load № 1 (A) Imbalance Factor = 100 x = 16 %

8100 - 6800

8100