Understanding and Troubleshooting DJ Tripping in ARNO Fitted Railway Locomotives

Understanding and Troubleshooting DJ Tripping in ARNO Fitted Railway Locomotives

The Disjoncteur (DJ), serving as the primary circuit breaker in an electric locomotive, plays a pivotal role in safeguarding its intricate electrical systems. This critical component is designed to interrupt the flow of power in the event of a fault, thereby preventing potential damage to valuable equipment and ensuring the overall safety of railway operations . When the DJ trips, it signifies an electrical irregularity that demands immediate attention and a systematic approach to identify and rectify the underlying cause .  

In locomotives equipped with an Alternating current Rotating machine Non-excited (ARNO) system, understanding the interplay between the main power circuits and the auxiliary systems is particularly important. The ARNO system is responsible for converting the single-phase Alternating Current (AC) supplied from the Overhead Equipment (OHE) into the three-phase AC required to operate various auxiliary machines essential for the locomotive's functionality, such as cooling blowers and motors . Failures within the ARNO system or the auxiliary components it powers can also trigger the DJ to trip as a protective measure, highlighting the interconnectedness of the locomotive's electrical architecture. Therefore, a comprehensive understanding of the common reasons behind DJ tripping, especially concerning the ARNO system and other vital locomotive elements, is indispensable for efficient maintenance practices and minimizing disruptions to railway services.  

When the DJ trips, it acts as an indicator of a problem within a specific area or component of the locomotive's complex electrical network. Recognizing the different scenarios under which tripping occurs allows maintenance personnel to adopt a focused and effective troubleshooting strategy.

To facilitate a clear understanding of the subsequent discussion, a glossary of abbreviations commonly used in the context of ARNO-fitted locomotives is provided below:

Abbreviation	Full Form (if known)	Description
BLDJ	Battery Link Disjoncteur	A switch to close or open the DJ using battery power .
BLRDJ	Battery Link Relay Disjoncteur	A button to press for closing the DJ .
BP2DJ	Button Push 2 Disjoncteur	Another button to press for closing the DJ .
LSDJ	Lamp Signal Disjoncteur	An indication lamp for the DJ status .
UA meter	Unknown Ammeter meter	A meter indicating current, possibly related to traction motors .
LSCHBA	Lamp Signal Circuit High Battery Alarm	An indication lamp possibly related to the battery charging circuit .
OHE	Overhead Equipment	The system that supplies electric power to the locomotive .
Pantograph	Current collector	A device mounted on the roof to collect power from the OHE .
TLC	Traction Loco Controller	Personnel to be informed about technical issues .
GR	Gear Ratio/Group Regulator	Possibly refers to the tap changer or a similar control mechanism .
SR	Subsidiary Rules	Railway operating rules and procedures .
MTDJ	Main Transformer Disjoncteur	A circuit breaker associated with the main transformer .
QLM	Main Overload relay	A relay protecting the main transformer from overload .
QOA	Overload relay for Auxiliaries	A relay providing overload protection for auxiliary circuits .
QLA	Low voltage relay for Auxiliaries	A relay that trips on low voltage in the auxiliary circuits .
RS pressure	Reservoir pressure	Air pressure in the reservoir system .
HQOA	Handle for QOA	A switch or control for the QOA relay .
HQOP	Handle for QOP	A switch or control for the QOP relay (Main Earth Fault Relay) .
Q45 relay	Safety relay	A relay in the DJ closing circuit .
ARNO	Alternating current Rotating machine Non-excited	A rotary converter that converts single-phase AC to three-phase AC .
QCVAR	Relay for Capacitor Voltage Auto Regulation	A relay associated with the ARNO system's voltage regulation .
C118	Contactor 118	A contactor in the ARNO starting circuit .
R118	Resistor 118	A resistor likely associated with the ARNO system .
Q30	No Volt Relay	A relay that trips the DJ if the OHE voltage is lost .
MPH	Miles Per Hour (Likely a typo and refers to a motor or blower)	In this context, likely refers to a motor or blower, not speed .
MVSL-1-2	Motor Ventilator Static Low speed - 1 & 2	Auxiliary motors/blowers for cooling .
HVSL-1-2	Handle for Motor Ventilator Static Low speed - 1 & 2	Switches for controlling MVSL-1 & 2 .
MVRH	Motor Ventilator Resistance Housing	A blower motor for cooling the dynamic braking resistors .
HVRH	Handle for Motor Ventilator Resistance Housing	A switch for controlling MVRH .
MVMT-1-2	Motor Ventilator Traction Motor - 1 & 2	Blower motors for cooling the traction motors .
HVMT-1-2	Handle for Motor Ventilator Traction Motor - 1 & 2	Switches for controlling MVMT-1 & 2 .
MVSI-1-2	Motor Ventilator Static Inverter - 1 & 2	Blowers associated with the static inverter system .
HVSI-1-2	Handle for Motor Ventilator Static Inverter - 1 & 2	Switches for controlling MVSI-1 & 2 .
SMGR	Shaft Motor Gear Regulator	The motor that drives the tap changer mechanism .
C105, C106, C107	Contactor 105, 106, 107	Contactors associated with auxiliary motors/blowers .
BLVMT	Battery Link Ventilator Motor Traction	A switch to turn on the blower motors using battery power .
QTD105, QTD106	Timer Delay Relay 105, 106	Time delay relays likely associated with contactors C105 and C106 .
C101, C102, C103	Contactor 101, 102, 103 (Likely MCP Contactors)	Contactors, possibly Main Compressor Plant (MCP) contactors .
BLCP(D)	Battery Link Compressor (Direct)	A switch to directly turn on the compressor using battery power .
CCA fuse	Copper Clad Aluminum fuse	A type of fuse used for overcurrent protection .
Q100	Relay 100 (Battery Voltage Supervisor Relay)	A relay that monitors the battery voltage .
Q118	Auxiliary Protection Relay	A time delay relay that trips the DJ in case of auxiliary failure .
TFP	Transformer Oil Pump	A pump to circulate oil for cooling the transformer .
DBR	Dynamic Brake Resistors	Resistors used for dynamic braking .

 

Troubleshooting DJ Tripping: A Scenario-Based Guide

This section provides a detailed analysis of each DJ tripping scenario outlined in the provided document, including the indications, potential defects, and troubleshooting procedures.

3.1 Tripping in No Tension on Line

This scenario occurs when the locomotive attempts to draw power from the OHE when there is no voltage present.

Indications: The Lamp Signal Disjoncteur (LSDJ) is extinguished when the Battery Link Disjoncteur (BLDJ) is turned ON and the Battery Link Relay Disjoncteur/Button Push 2 Disjoncteur (BLRDJ/BP2DJ) is pressed. The UA meter does not show any deviation, the Lamp Signal Circuit High Battery Alarm (LSCHBA) does not extinguish, and the LSDJ glows again after releasing the BLRDJ/BP2DJ.

Defects: The potential causes for this tripping include:

• Defect in OHE equipments: A break or fault in the overhead power supply system would prevent the locomotive from receiving power .  
• Pantograph not touching with contact wire: If the pantograph fails to make physical contact with the contact wire of the OHE, no current can be drawn . This could be due to the pantograph not being raised or a mechanical issue preventing proper contact.  
• Defect in roof equipments or any foreign material on roof: Damage to the equipment mounted on the locomotive's roof, such as insulators or connecting bars, or the presence of foreign material could create an electrical fault or prevent the pantograph from operating correctly.

Troubleshooting: The recommended steps to address this issue are: i. If panto is not touching to contact wire, try with other panto or trouble shoot for panto not rising: If one pantograph is not making contact, attempting to raise the other pantograph might resolve the issue, assuming the problem is isolated to a single pantograph. If neither pantograph rises, the problem lies in the pantograph raising mechanism itself. ii. If pantograph is in raised condition then lower the pantograph and watch the sparking or chattering sound from pantograph: Lowering the pantograph and observing its interaction with the contact wire can provide clues about the connection quality. Sparking or chattering might indicate intermittent contact due to OHE issues or a faulty pantograph. iii. Sparking / chattering sound is not found then inform TLC and wait for restorsion of power by taking proper protction as per GR/SR: If the pantograph appears to be making good contact without any unusual sounds, the issue likely lies with the OHE power supply. In such cases, the Traction Loco Controller (TLC) should be informed, and the crew should wait for the power to be restored, following the General and Subsidiary Rules (GR/SR) for safety procedures . iv. If sparking / chattering sound is found then raise other panto and try. If success then work the train: If intermittent contact is observed with one pantograph, raising the other pantograph might establish a stable power connection, allowing the train to proceed. v. If not success then check loco roof for any foreign body or loco roof equipment or cut in roof bar or panto whether touching to contact wire: If the second pantograph also fails to establish a stable connection, a physical inspection of the locomotive's roof is necessary to check for any obstructions, damage to roof-mounted equipment, or issues with the pantograph's ability to reach the contact wire. vi. If any foreign body is noticed or loco roof equipment is touching to roof or cut in OHE is noticed immediately stop the train, secure the loco as per GR/SR and contact TPC and attend the trouble: If any foreign object, malfunctioning roof equipment, or a visible cut in the OHE is identified, the train must be stopped immediately. The locomotive should be secured according to safety regulations (GR/SR), and the Traffic Power Controller (TPC) should be contacted to address the issue.  

The absence of UA meter deviation suggests that no significant current is being drawn, which aligns with the pantograph not making contact or a lack of power supply from the OHE. The LSCHBA remaining unextinguished could indicate that the battery charging circuit is not being activated, which would normally occur when the locomotive is drawing power from the OHE. The LSDJ glowing again after releasing the BLRDJ/BP2DJ indicates that the DJ is opening because the conditions for maintaining it closed are not met.

3.2. Operation –A – Beginning

This scenario describes a situation where the DJ trips immediately after being closed.

Indications: After putting ON the BLDJ and pressing BLRDJ/BP2DJ, the LSDJ extinguishes momentarily, and the DJ trips immediately, causing the LSDJ to glow again (flickers).

Defects: The primary defect indicated by this behavior is a cut in the Main Transformer Disjoncteur (MTDJ) branch.

Troubleshooting: The troubleshooting steps involve checking components in the auxiliary power circuit: i. Check QLM, QOA & QLA. If any drops, trouble shoots accordingly: The QLM (Main Overload relay), QOA (Overload relay for Auxiliaries), and QLA (Low voltage relay for Auxiliaries) are protective relays. If any of these have tripped (indicated by a dropped target), it suggests an overload or fault in the main transformer or auxiliary circuits . The specific relay that has dropped will guide further troubleshooting. ii. If normal then - Check RS pressure, it should be 8kg/cm2: If the relays are normal, the Reservoir pressure (RS pressure) should be checked. Insufficient air pressure might prevent the DJ from remaining closed . iii. If unsuccessful, then put HQOA on ‘0’ position,HQOP-1 +2 OFF and try to close DJ. If success then trouble shoot accordingly: If the DJ still trips, putting the Handle for QOA (HQOA) to the '0' position and turning OFF the Handle for QOP (HQOP) positions 1 and 2 isolates certain auxiliary protection circuits. If the DJ closes successfully in this configuration, it indicates a fault within the isolated circuits. Further troubleshooting would then focus on these circuits . iv. If QLM or QLA drops then follow trouble shooting accordingly: If the QLM or QLA relay target has dropped, specific troubleshooting procedures for those relays should be followed, as they indicate issues with the main transformer or auxiliary power supply, respectively . v. If no relay target drops then try from rear cab: If no relay targets are dropped in the leading cab, attempting to close the DJ from the rear cab might help isolate the problem, potentially indicating an issue with the control circuits specific to one of the cabs. vi. if unsuccessful, drain out MR/RS pressure and try to restart from begining: If all previous attempts fail, draining the Main Reservoir (MR)/Reservoir pressure (RS pressure) and restarting the entire process from the beginning might clear a temporary fault or reset some control logic. vii. If unsuccessful then ask for assistance: If the problem persists after all these steps, it indicates a more complex issue requiring expert intervention.  

The immediate tripping of the DJ suggests a severe fault that is detected as soon as power is applied. A cut in the MTDJ branch implies an interruption or short circuit in the power supply path to or from the main transformer. The checks on QLM, QOA, and QLA aim to identify overloads or earth faults in the primary power or auxiliary circuits that could be causing the DJ to trip.

3.3. Operation – A – Ending

This scenario describes the DJ tripping after a short delay while the locomotive is in operation.

Indications: After putting 'ON' BLDJ and pressing BLRDJ/BP2DJ, the LSDJ extinguishes, the UA meter deviates (indicating current flow), the LSCHBA does not extinguish, and the DJ trips within 15 seconds.

Defect: The likely defects in this case are related to the ARNO system or the Relay for Capacitor Voltage Auto Regulation (QCVAR).

Troubleshooting: The troubleshooting involves checking for abnormalities in the ARNO system and isolating the QCVAR: Press BP2DJ for 4 seconds and check any smoke, fire, burning smell, abnormal sound from ARNO, Contactor 118 (C118), or Resistor 118 (R118) or not. This step aims to identify any obvious signs of failure within the ARNO converter and its associated components .  

i. If any abnormality is found then ask for assistance: Any signs of smoke, fire, burning smell, or abnormal sounds indicate a significant fault requiring expert attention. ii. If Arno is ok then put HQCVAR on“0” and close DJ: If no abnormalities are observed with the ARNO system, putting the Handle for QCVAR (HQCVAR) to the "0" position isolates the QCVAR from the circuit. Then, attempting to close the DJ helps determine if the QCVAR is the cause of the tripping . iii. work the train by checking the function of ARNO and Battery Voltage (85V- 110V): If the DJ remains closed with HQCVAR at "0", the train can be operated, but the function of the ARNO system and the battery voltage should be closely monitored.  

Note: Don’t wedge the Q45 relay if HQCVAR is on ‘0’. Wedging safety relays should only be done under specific circumstances and with caution. With HQCVAR off, the protection provided by QCVAR is bypassed, and wedging another safety relay might compromise overall safety.

The UA meter deviating indicates that the locomotive is initially drawing power, suggesting the OHE and pantograph are functioning correctly. The LSCHBA remaining unextinguished might be normal during operation, depending on the state of charge of the battery and the load on the auxiliary circuits. The DJ tripping after a short delay points towards a problem that develops or becomes significant after the ARNO system starts operating or the locomotive begins to draw a certain level of current.

3.4. Operation – B

Operation 'B' likely refers to a specific operating mode or condition of the locomotive.

3.4.1. Operation ‘B’, Part -1

This scenario describes the DJ tripping immediately after the BLRDJ is released.

Indications: After putting 'ON' BLDJ and pressing BLRDJ, both the LSDJ and LSCHBA extinguish, but the DJ trips after releasing BLRDJ.

Defect: The potential causes are trouble in the No Volt Relay (Q30) or low OHE voltage.

Troubleshooting: The troubleshooting focuses on checking the OHE voltage and the functionality of the Q30 relay: Put 'ON' BLDJ, press BLRDJ and then i. Check OHE voltage. If OHE voltage is less than 17.5 KV then wait for restores: Low OHE voltage can cause the DJ to trip. If the voltage is below the acceptable threshold (17.5 KV in this case), the crew should wait for the power supply to be restored to the correct level . ii. If OHE voltage is OK the defect in Q30 relay, then: If the OHE voltage is within the normal range, the issue is likely with the Q30 relay, which is designed to trip the DJ if the OHE voltage is lost . * Tap gently on Q30 relay and try to close DJ: Gently tapping the Q30 relay might temporarily resolve a sticking contact issue. * If unsuccessful then wedge relay Q45 in energised condition, clear block section by taking the following precautions: If tapping Q30 does not work, wedging the Q45 relay in its energized condition might bypass a safety interlock preventing the DJ from staying closed. However, this should be done with extreme caution and only to clear the block section, following specific precautions: * Check working of MVSI-1 and MVSI-2 frequently: Monitor the operation of the Motor Ventilator Static Inverter blowers frequently . * Observe OHE voltage above 17.5 KV and sound of ARNO: Ensure the OHE voltage remains adequate and the ARNO system is functioning normally . * At neutral section open BLDJ at DJ opening board and close BLDJ only at DJ closing board: Exercise caution at neutral sections of the OHE by opening the BLDJ before entering and closing it only after fully passing the section.  

Note: i. Do not wedge Q 45 if HQCVAR is on ‘0’(ZERO): As mentioned earlier, wedging safety relays should be avoided when associated protection circuits are already bypassed. ii. Check GR on ‘0’ before closing DJ: Ensure the Gear Ratio/Group Regulator (likely the tap changer) is in the '0' position before attempting to close the DJ . iii. Do not use DBR if Q30 is defective: The Dynamic Brake Resistors (DBR) should not be used if the Q30 relay is suspected to be faulty, as it might affect the dynamic braking system .  

The extinguishing of both LSDJ and LSCHBA upon pressing BLRDJ suggests that the initial conditions for closing the DJ are met. However, the immediate tripping after releasing BLRDJ indicates that a holding circuit or mechanism is failing, which could be due to the Q30 relay not remaining energized or an issue with the power supply itself.

3.4.2. Operation B Part-2

This scenario describes the DJ tripping after a short delay (within 15 seconds) after the BLRDJ is released.

Indications: LSDJ and LSCHBA extinguish. DJ will trip after releasing BLRDJ within 15 seconds.

Defects: The potential defects include issues with the MPH (likely a motor/blower), MVSL-1-2 (Motor Ventilator Static Low speed - 1 & 2) and its relays, and a Normally Open (N/O) interlock of QCVAR on the Q118 branch.

Troubleshooting: The troubleshooting involves isolating auxiliary components and checking their functionality: Put, Handle for Motor Ventilator Static Low speed - 1 & 2 (HVSL - 1 & 2), Handle for MPH (HPH) on ‘3’ & HQCVAR on ‘0’ and close DJ and check smoke, burning smell and fire from any auxiliary. If any abnormality is found then isolate defective equipment. If no abnormality is found then

i. Check working of MVSL- 1 & 2: Verify if the low-speed static inverter blowers are functioning correctly . ii. If any MVSL is not working then trip DJ, put concerned HVSL, Handle for Motor Ventilator Traction (HVMT), Handle for Motor Ventilator Static Inverter (HVSI) on ‘0’. and rest normal position. Close DJ, clear block section if possible & inform TLC: If one of the MVSL blowers is not working, trip the DJ and isolate the corresponding blower and its controls (HVSL, HVMT, HVSI) by setting their switches to '0'. Then, attempt to close the DJ and proceed to clear the block section if possible, while informing the TLC. iii. If both MVSL not working, ask for assistance: If neither of the MVSL blowers is operational, it indicates a significant issue requiring expert intervention. iv. If both MVSL are working Trip DJ then put HVSL-1 & HVSL-2 on position‘1’ one by one and close DJ: If both MVSL blowers are working, trip the DJ and then try operating each blower individually by setting its HVSL switch to position '1' and closing the DJ. This helps identify if one of the blowers is causing the DJ to trip when it starts. v. If DJ trips then put concerned switch on position ‘3’ and work the train observing the working of concerning blower keeping other switch in position ‘1’: If the DJ trips when a specific MVSL is turned on (HVSL at position '1'), set the corresponding HVSL switch to position '3' (which might engage a higher speed or different operating mode) and operate the train while closely monitoring the blower's performance, keeping the other HVSL switch at position '1'. vi. If DJ does not trip, trip DJ then put HPH on ‘1’ and close DJ. If DJ trips then put HPH on ‘0’ and clear the block section (keeping watch on TFP oil level & leakage if any) with restricted TM current ( 900 amp. for 5 minutes & cont. 500 amp.) and inform TLC: If the DJ does not trip when the MVSL blowers are tested, trip the DJ and then turn on the MPH (HPH to '1'). If this causes the DJ to trip, turn off the MPH (HPH to '0') and clear the block section with restricted traction motor (TM) current, while observing the Transformer Oil Pump (TFP) oil level for any abnormalities, and inform the TLC . vii. If DJ does not trip, trip DJ then put HQCVAR on ‘1’: If the DJ still does not trip, trip it again and then set the HQCVAR to position '1'. viii. If DJ trips then put HQCVAR on ‘0’ and work the train watching the working of ARNO. (QCVAR under interlock on Q118 branch is defective): If the DJ trips when HQCVAR is set to '1', it indicates a defect in the QCVAR or its interlock on the Q118 branch. In this case, set HQCVAR back to '0' and operate the train while carefully monitoring the ARNO system.  

Note:

• Before putting switches on Position – ‘3’ operate all the above switches 2 to 3 times to avoid bad contact from switches: This ensures proper electrical contact within the switches.

The DJ tripping after a short delay suggests that the fault develops as certain auxiliary systems come online or reach a specific operating condition. The troubleshooting process aims to isolate the defective component by systematically testing each auxiliary system.

3.5. Tripping in operation – ‘0’

Operation '0' likely refers to a specific operational state, possibly when the locomotive is stationary or at idle.

Indications: DJ trips within 15 seconds after putting Battery Link Ventilator Motor Traction (BLVMT) ON.

Defect: The potential defects are related to the Motor Ventilator Resistance Housing (MVRH), Motor Ventilator Traction Motor - 1 and 2 (MVMT-1and MVMT-2), or their associated relays.

Troubleshooting: The troubleshooting involves isolating and testing these blower motors: Put ‘OFF’ BLVMT switch Put Handle for Motor Ventilator Traction (HVMT) – 1 & 2, Handle for Motor Ventilator Resistance Housing (HVRH) on position ‘3’ and close DJ, put BLVMT ‘ON’ and check smoke, burning smell and fire and the function of MVMT-1&2, and MVRH. If any abnormality is found then isolate defective equipment. If any blower is not working:-

If MVRH not working – Keep HVRH on ‘0’ and observe opening of Contactor 107 (C107), then close DJ clear block section by 5th notch observing TFP oil level and inform TLC . If MVMT–1 is not working – Put HVMT-1 , Handle for Motor Ventilator Static Inverter (HVSI)-1 and Handle for Motor Ventilator Static Low speed (HVSL)-1 on ‘0’ position, check opening of Contactor 105 (C105). Close DJ, clear block section by one block if possible and inform TLC . If MVMT–2 is not working – keep HVMT -2, HVSI-2 and HVSL-2 on ‘0’ position, check opening of Contactor 106 (C106). Close DJ clear block section by one block if possible and inform TLC . IF ALL BLOWERS ARE WORKING: - Then find out the defective relayby keeping HVMT 1&2, HVRH on Position ‘1’ one by one. If DJ trips then put that switch on position ‘3’. Rest switches in normal position and work the train keeping sharp watch on the concerning blower.  

The DJ tripping shortly after turning on the blowers suggests an issue with one or more of these motors or their control circuits. The troubleshooting aims to identify the faulty blower by isolating and testing them individually.

3.6. Tripping in operation – ‘1 - A’

Operation '1 - A' likely refers to the locomotive operating at the first notch of the power controller.

Indications: DJ tripping on 1st notch.

Defects: The potential defects are related to the Motor Ventilator Static Inverter - 1 and 2 (MVSI-1,MVSI-2) or their relays, and the Shaft Motor Gear Regulator (SMGR).

Troubleshooting: The troubleshooting involves checking the MVSI blowers and the SMGR: Check smoke, fire from MVSI-1, MVSI-2. If any abnormality is found then isolate defective motor as per procedure.

i. Put both HVSI – 1 & 2 on position ‘3’close DJ and confirm about the working of MVSI- 1 & 2: Setting the switches for both MVSI blowers to position '3' and closing the DJ helps confirm if the blowers are functioning correctly at a higher setting . ii. If both MVSI not working- Ask for assistance: If neither MVSI blower is operational, expert assistance is required. iii. If one MVSI not working – then keep concerning HVSI, HVMT, HVSL on position ‘0’ rest normal position close DJ and clear the block section if possible and inform TLC: If one MVSI blower is not working, isolate it by setting its associated switches (HVSI, HVMT, HVSL) to '0', then close the DJ and proceed to clear the block section if possible, while informing the TLC. iv. If both MVSI are working- then put HVSI-1 and 2 in position ‘1’ one by one, take one notch: If both MVSI blowers are working, test them individually at the first notch by setting their HVSI switches to position '1' one at a time. v. If DJ trips on 1 st notch then put back that HVSI on position ‘3’ rest normal, close DJ and – work the train keeping sharp watch on concerning MVSI: If the DJ trips when one of the MVSI blowers is engaged at the first notch, set the corresponding HVSI switch back to position '3' and operate the train while closely monitoring that blower. If DJ trips on1st notch in HVSI-1 &2 on position –‘3’ Then defect is in SMGR, keep both HVSI on position – ‘1’ Clear the block section by manual control of GR and inform TLC. If the DJ trips even with both MVSI blowers running at position '3' at the first notch, the defect might be with the SMGR. In this case, keep both HVSI switches at position '1', clear the block section using manual control of the Gear Ratio/Group Regulator (GR), and inform the TLC .  

Tripping at the first notch suggests a problem that manifests when the locomotive starts to draw power for traction. The MVSI blowers, being associated with the static inverter which provides power for auxiliary systems, could be drawing excessive current or have a fault. The SMGR, responsible for controlling the tap changer and thus the voltage supplied to the traction motors, could also be the cause if it's malfunctioning at the initial stage of power application.

3.7.Tripping in Operation – ‘1 - B’

Operation '1 - B' likely refers to the locomotive operating at the sixth notch of the power controller.

Indications: DJ trip within 15 second on 6th notch.

Defect: The potential defects are that the Contactors 105, 106, and 107 (C105, C106 and C107) are open or their Normally Open (N/O) interlock is defective on the Q118 branch. These contactors are associated with the auxiliary blower motors .  

Troubleshooting: The troubleshooting involves checking the closing of these contactors and their associated relays: Close DJ, put ‘ON’ BLVMT and Check closing of C105, C106 and C107 If any blower contactors is not closing, then –

i. Check switch position of HVMT-1 & 2 and HVRH in position ‘1’ or ‘3’: Ensure the switches for the traction motor blowers (HVMT-1 & 2) and the resistance housing blower (HVRH) are in either position '1' or '3', as these positions likely enable the operation of the associated contactors . ii. If C107, C105 & C106 are denergised then wedge C107 Contactor and try: If the contactors are not closing (de-energized), wedging the C107 contactor might temporarily force it to close. iii. If C105 & C106 are denergised then check QTD105, if denergised then wedge it in energised condition.If it is energised then wedge C105 contactor and ensure closing of C106 contactor: If C105 and C106 are de-energized, check the status of the Timer Delay Relay 105 (QTD105). If it's also de-energized, wedge it in the energized condition. If QTD105 is energized, then wedge the C105 contactor and ensure that the C106 contactor closes. iv. If C106 deenergised then check QTD106, if it is denergised then wedge it in energised condition. If it is energised then wedge C106 contactor and work the train: If C106 is de-energized, check the Timer Delay Relay 106 (QTD106). If it's de-energized, wedge it in the energized condition. If QTD106 is energized, then wedge the C106 contactor and operate the train.  

Note: Use correct wedge during wedging of EM contactor. Put BLVMT ‘ON’, Close DJ by Q118 manually and pressing BP-2 DJ if one or more than one blower contactor(C105, C106 & C107) is wedged. (in Microprocessor Loco put concerning switch on position- ‘3’ close DJ) and work the train with close watch on wedged contactor and concerning blower. Check concerned motor functioning. Wedging contactors is a temporary measure and requires careful monitoring of the affected components. Manually closing the DJ using Q118 and BP-2DJ, and putting the corresponding switch to position '3' in microprocessor-controlled locomotives, are specific procedures to be followed when contactors are wedged.

If all three blowers contactors are closing and blowers are working then trip DJ, keep both HVMT on position-‘3’, close DJ and takes 6 notches. i. If DJ trips, C107 N/O interlock defect. Clear block section up to 5th notch: If the DJ trips after taking the 6th notch with all blowers working, the Normally Open (N/O) interlock of C107 might be defective. In this case, clear the block section while limiting the power to a maximum of the 5th notch. ii. If load is not permitted then wedge Q118, close DJ, clear block section, inform TLC keeping sharp watch on TFP oil level and working of auxiliaries: If operating even at the 5th notch is not permissible, wedging the Q118 relay might be necessary to bypass a protection circuit. If this is done, close the DJ, clear the block section, inform the TLC, and closely monitor the TFP oil level and the functioning of all auxiliary equipment. iii. If DJ not trips put HVMT switches to position-‘1’ one by one. Take 6th notches: If the DJ does not trip after the initial checks, try setting the HVMT switches to position '1' one by one and taking the 6th notch. iv. If DJ trips put that HVMT at position ‘3’ and rest HVMT at position –‘1’ and observe function of that blower: If the DJ trips when one of the HVMT switches is at position '1', set that switch to position '3' and keep the other HVMT switch at position '1' to observe the functioning of the corresponding blower. v. If C105,C106,C107 not closing then check closing of Contactor 101, 102, 103 (C101,C102,C103) by putting BLCP(D) ‘ON’. If MCP contactors are also not closing then check CCA fuse and relay Q100. If problem is found in CCA or Q100 then trouble shoot accordingly: If the blower contactors (C105, C106, C107) are not closing, check if the Main Compressor Plant (MCP) contactors (C101, C102, C103) are closing by turning on the Battery Link Compressor (Direct) switch (BLCP(D)). If the MCP contactors also fail to close, inspect the Copper Clad Aluminum (CCA) fuse and the Q100 relay (Battery Voltage Supervisor Relay). Troubleshoot any issues found with these components .  

Note: Before putting Switches on position-‘3’, operate all the above switches two to three times to avoid bad contact from switches. This ensures proper electrical connection.

Tripping at the 6th notch suggests a problem that becomes apparent when the locomotive is under a moderate load. The contactors and interlocks associated with the auxiliary blowers are crucial for maintaining the temperature of the traction motors and other equipment. A failure in these components or their control circuits can lead to overheating and subsequent DJ tripping as a protective measure.

Conclusion

DJ tripping in an ARNO-fitted locomotive is a critical safety mechanism that indicates an abnormality within the electrical system. The various scenarios outlined provide a structured approach to diagnosing and addressing these issues, ranging from problems with the external power supply and pantograph contact to faults within the ARNO system and auxiliary components like blowers and their associated control circuits. By understanding the indications, potential defects, and troubleshooting procedures for each scenario, railway technicians can effectively identify and resolve the underlying causes of DJ tripping, ensuring the safe and reliable operation of these locomotives. The systematic approach to troubleshooting, involving checks of relays, contactors, blowers, and power supply parameters, highlights the complex interplay of electrical and mechanical systems within the locomotive. Adherence to safety protocols and proper reporting to the TLC are crucial aspects of managing DJ tripping incidents and maintaining the integrity of railway operations.