Payload Meter III - Section 60 08/06 OM6008 Page 60-8 PLM III monitors the status of the key switch. 24VDC indicates that the key switch is ON. Open indicates the key switch is OFF. The payload meter does not receive its electrical power from the key switch cir- cuit. The payload meter will remain on for several seconds after the key switch is removed. When the key switch power is removed, payload meter per- forms a series of internal memory operations before turning itself off. To allow for these operations, the key switch must be turned off for at least 15 seconds before turning the key switch back ON.
The payload meter will automatically reset itself without error if not enough time is given for these operations. The dis- play may blink briefly. Key Switch Input Load Lights PLM III 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 24 VDC outputs. A 24 VDC signal from the pay- load meter powers the relay coil and connects bat- tery 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 cir- cuit 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 load lights progressively indicate to the shovel operator the approximate weight of the material in the truck. The payload meter receives its power from the bat- tery circuit on the truck. Removing battery power from the payload meter before removing the key switch and waiting 15 seconds may result in lost haul cycle data.
The payload meter turns itself off approxi- mately 15 seconds after the key switch 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 24 VDC at 1 to 2 amps, depending on options. The payload meter is designed to turn itself off if the sup- ply voltage rises above 36 VDC. The payload meter is also protected by a 5 amp circuit breaker located in the junction box. 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 cur- rent 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 cur- rent 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. Power to the load lights comes from the same battery circuit. The load lights are powered through a relay. The key switch circuit controls the relay. The load lights are also protected by a 15 amp circuit breaker in the junction box.
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%.