EJECTOR AS 7C6445 - Caterpillar

Connections For The 9Y-2921 Relay
Illustration 7 g00312784
(A) - VDC. (B) + VDC. (C) 9Y-2921 Relay . (D) Terminal "85". (E) Terminal "86". (F) Terminal "87A". (G) Terminal "30". (H) Terminal "87". (I) Annunciator Panel.Connect the Terminal 4 "Coil" to the relay terminal "86".Connect the + VDC to the relay terminal "30" and the relay terminal "85".Connect the relay terminal "87" to the annunciator panel.The connection at the Terminal 4 "Coil" should be left open when the pyrometer's coil is not being used. Make sure that the thermocouple wire to channel "0" is connected by a jumper wire or connected to a thermocouple.Operation
Advancing The Channels
Illustration 8 g00312846
Once the pyrometer is powered up, the pyrometer will start reading the temperature of channel "0". In order to read the temperatures of the other eight channels, push the "PUSH TO ADVANCE" switch. The "PUSH TO ADVANCE" switch is located in the middle of the front panel. When the switch is actuated, the pyrometer's readout will increment to the next channel.Selector Switch
Illustration 9 g00312863
The selector switch is located on the lower left side on the back side of the pyrometer. Set the selector switch to the "IN-LINE" position for six cylinder in-line engines and eight cylinder in-line engines.For 12 cylinder engines and 16 cylinder engines which use two pyrometers, set the selector switch on one pyrometer to the "V-EVEN" position. Set the other pyrometer to the "V-ODD" position in order to correspond with the thermocouple wires that enter the individual pyrometers.Setpoint Adjustment
Illustration 10 g00313148
The high temperature alarm setpoint for channel "0" is read by pressing the "PUSH TO READ" button. In order to adjust the setpoint, first press the "PUSH TO READ" button. Next, unscrew the cap from the set point potentiometer. Then adjust the potentiometer setting with a small screwdriver until the display matches the desired temperature. Turn the potentiometer clockwise in order to increase the desired temperature. Turn the potentiometer counterclockwise in order to decrease the desired temperature.
Table 1
Recommended High Temperature Setpoints    
High Turbocharger Exhaust Inlet Temperature (Standard)    
630°C (1166.0°F)    
High Turbocharger Exhaust Inlet Temperature (High Output)    
650°C (1202.0°F)    
High Turbocharger Exhaust Inlet Temperature (Heavy Fuel)    
550°C (1022.0°F)    The output switch will be activated when the temperature reading at channel "0" exceeds the desired temperature setting that was set previously.Note: The setting is retained until the potentiometer setting is changed.Testing The Thermocouple Leads
Illustration 11 g00313183
Whenever it is necessary to check the wiring of the thermocouple, disconnect the thermocouple's wiring at the back of the pyrometer. This will prevent damage to the pyrometer's sensitive circuitry.Troubleshooting
Thermocouple Wiring Checks
Disconnect the leads from the back of the pyrometer.
Check the resistance of the leads from thermocouple when the thermocouple is connected. A low resistance should be present. The actual value will depend on the length of the leads and the temperature of the thermocouple. If an open circuit is indicated, check the resistance of the thermocouple in order to determine the location of the open circuit. The open circuit could be in the