SHAFT-FAN 4P3875 - Caterpillar

Illustration 1 g00481725
Functional Block Diagram Of AC Voltage Display In EMCP II+
Illustration 2 g00436699
Relays In Relay Module (1) Jumper block
Table 1
AC Voltage Range Selection    
GSC+ P020 Setpoint    External Potent- ial Trans-
former    AC Trans-
former Box (ATB+) Input Voltage Range    GSC+ Internal Multipl- ier    Jumper    
700     None     0 - 700     5     Required    
150     None     0 - 150     1     None    
300     2:1     0 - 150     2     None    
500     3.33:1     0 - 150     3.33     None    
600     4:1     0 - 150     4     None    
750     5:1     0 - 150     5     None    
3000     20:1     0 - 150     20     None    
4500     30:1     0 - 150     30     None    
5250     35:1     0 - 150     35     None    
9000     60:1     0 - 150     60     None    
15000     100:1     0 - 150     100     None    
18000     120:1     0 - 150     120     None    
30000     200:1     0 - 150     200     None    Jumper block (1) is used to select the voltage range of the voltmeter of the GSC+. Jumper block (1) is installed for systems with 700 volts full scale AC inputs. Jumper block (1) is NOT installed for systems with 150 volts full scale AC inputs or for any unit with external potential transformers. The relay module comes from the factory already equipped with the jumper block (1) installed.Jumper block (1) is easily removed by grasping and pulling it. Jumper block (1) is easily installed by aligning and then pushing in. If a jumper block is required but is not available, three separate jumpers can be substituted. Each of the three manufactured jumpers connect a pair of pins. A pair of pins must not touch another pair of pins.The relay module must be removed from the GSC+ to gain access to the circuit board and jumper block (1). See Testing And Adjusting, "Relay Module - Replace".The P020 setpoint determines the proper AC voltage range and the internal multiplier that are used by the GSC+ for calculating AC voltage. The GSC+ uses the internal multiplier to compensate for the turns ratio of the external potential transformers, if present. The turns ratio of the external potential transformer must match this internal multiplier to ensure accurate AC voltage calculation by the GSC+.The jumper block (located in the relay module) connects a divide-by-five circuit to the AC voltage input of the GSC+. The divide-by-five circuit reduces the AC voltage input to a manageable level for the GSC+ when P020 is 700. When setpoint P020 is 700, a multiplier of five is needed to compensate for the presence of the divide-by-five circuit (jumper installed) even though no external potential transformer is present.Note: In order to prevent inaccurate voltage calculation by the