Eurotherm DC speed controller repair scope:
SSD590 series, SSD590+ series, SSD590C, SSD590P, SSD512C, SSD514C series
The SSD DC speed controller features built-in control, allowing motor start/stop and speed control via the operation panel. It includes a built-in ultra-low noise fan and adds Devicenet, CAN Open, and Lonworks bus communication capabilities. It can handle power up to 2700A, 660V (1-1500kW). It shares the same form factor as the 690+, with unified programming/parameter settings and communication methods. The analog DC regulator is single-phase 110-460Vac, with a 2-quadrant power supply for the 512 series and below, and a 4-quadrant supply for the 514 series. The voltage range is 100-200Vac, and the speed is limited by the armature current. The maximum current is below 32A.
Eurotherm DC speed controller fault analysis:
Model: Eurotherm 590 DC Speed Controller
Fault phenomenon: The machine alarms "FIELD FALL" when started. According to the manual, it is an excitation fault.
Cause of the fault: Upon opening the machine, check the D3 and D4 excitation output terminals. There is no excitation voltage output, which causes the power-on alarm "FTELD FALL".
Troubleshooting: After checking the circuit components of the excitation output circuit, no damaged electronic components were found. The focus was on checking the thyristor of the excitation output. After replacing the thyristor and restarting, the excitation voltage output was normal, around 160V.
One Eurotherm 590+ motor malfunctioned and was replaced by a new one purchased from Shanghai Chuanlian Electric Appliances. After inputting the original motor parameters, it worked well in local control mode, but it could not work in remote control mode. The fault symptom was that the operation information was flashing.
The inspection revealed that there was no input signal. The analog inputs showed 6V, and after confirming that the external digital inputs were working correctly, the analog inputs were changed from A1 and A4 to A1 and A3, and the system functioned normally. This confirmed that there were no issues with the external inputs.
According to the programming flowchart in the 590+ Chinese operation manual, the RAMP HOLD (118) menu content in the RAMPS input of the module is ON, which is a ramp hold. It can be basically determined that the 590+ cannot run because of the ramp hold. Check the condition of DIGITTAL INPUT2, which is C7. Check the C7 terminal and find that the two sub-circuits of C7 and C9 are connected together. After separating C7 from the C9 terminal, move the analog signal from A3 to A4. After the operating conditions are met, the 590+ works normally.
Therefore, it can be determined that the fault was caused by the ramp holding, which prevented 590+ from operating normally. The reason for this was the merging of the C9 and C7 lines!
Example 1
Fault phenomenon: Eurotherm 590 DC speed controller cannot adjust speed.
Inspection and analysis: Upon inspection, the +10V voltage reference power supply was approximately 2V, and the -10V voltage reference power supply was approximately -7V. One IC was found to be overheating; after replacement, the -10V power supply was normal, but the +10V power supply was +13V. Further measurement revealed two burnt-out surface-mount resistors near this IC. After replacement, the ±10V power supply was normal, and the machine operated normally when connected to the motor and speed adjusted.
Example 2
The fault is that the computer displays 0xf003 upon startup.
The problem persisted even after replacing the panel with a known good one, indicating the fault lay in the motherboard. A different working unit was then used to test the voltages at various points on the motherboard, and compared with the faulty unit. Abnormal voltages were found at points VP31 and VP32. Checking the components surrounding IC2 and IC339 revealed no abnormalities. Replacing IC339 restored the voltage, the 0XF003 alarm disappeared upon startup, and the unit operated normally. The normal voltages at each test point are as follows:
vp24 vp25 vp55 vp31 vp32 vp33 vp34 vp22 vp23
4.99v 196mv 0.4v 2.29v 2.5v 23mv -13.8v -1.827v -18mv
0xf003 indicates an auxiliary power supply fault. The fault point was sampled on the 590 power supply board. The above repair method involves comparing the voltage with that of a normal board, which is a way to make full use of existing data. Alternatively, if the fault point and detection circuit can be identified through rational analysis, the problem can also be solved.
More Eurotherm 590 DC speed controller repair examples
