Optional Equipment - Section 6 OM6008 02/03 Page 6-6 Payload Meter III Keyswitch Input PLMIII monitors the status of the keyswitch. 24vdc indicates that the keyswitch is on, open indicates the keyswitch is off. The payload meter does not receive its electrical power from the keyswitch circuit. The payload meter will remain on for several seconds after keyswitch is removed. When the keyswitch power is removed, payload meter performs a series of internal memory operations before turning itself off. To allow for these operations, the keyswitch should be turned off for at least 15 seconds before turning the keyswitch back on.
The payload meter will automatically reset itself without error if not enough time is given for these operations. The display may blink briefly. Load Lights PLMIII uses load lights to indicate to the shovel operator the approximate weight of the material in the truck. The load lights are illuminated only when the brake lock is applied. The lights are controlled by the payload meter through a series of relays in the junction box. The payload meter controls the relays with 24vdc outputs. A 24vdc signal from the payload meter powers the relay coil and connects battery power to the load light.
When the relay is not powered by the payload meter, a pre-warm resistor connects the load light to a reduced voltage. This circuit pre-warms the load light filaments and reduces the inrush current when the light is fully illuminated. This lengthens the operating life of the load lights. Payload Meter Power The payload meter receives its power from the battery circuit on the truck. Removing battery power from the payload meter before removing keyswitch and waiting 15 seconds may result in lost haul cycle data. The payload meter turns itself off approximately 15 seconds after the keyswitch power is removed.
Some haul cycle data will be lost if battery power is removed before waiting 15 seconds. The payload meter system operates at a nominal voltage of 24vdc at 1 to 2 amps depending on options. The payload meter is designed to turn itself off if the supply voltage rises above 36vdc. The payload meter is also protected by a 5 amp circuit breaker located in the junction box. Power to the load lights comes from the same battery circuit. The load lights are powered through a relay. The keyswitch circuit controls the relay. The load lights are also protected by a 15 amp circuit breaker in the junction box.
The load lights progressively indicate to the shovel operator the approximate weight of the material in the truck. A flashing green light indicates the next swingload will make the measured load greater than 50% of rated load. A solid green light indicates that the current load is greater than 50% of rated capacity. A flashing amber light indicates the next swingload will make the measured load greater than 90% of rated load. A solid amber light indicates that the current load is greater than 90% of rated capacity. A flashing red light indicates the next swingload will make the measured load greater than 105% of rated load.
A solid red light indicates that the current load is greater than 105% of rated capacity. The optimal loading target is a solid green and amber lights with a flashing red light. This indicates that the load is between 90% and 105% of rated load for the truck and the next swingload will load the truck over 105%.