LTI ServoOne Replacement and Troubleshooting

When replacing high-power liquid cooling modules, the liquid cooling design of ServoOne is crucial. The maximum internal coolant capacity of the equipment can reach 0.5 liters.

Interface specification: The liquid cooled interface has a 3/8-inch internal thread.

Leak prevention measures: It is strongly recommended to use a "drip proof quick connector" and adapter (to be provided by the user) for disassembly and connection when the coolant is full, in order to avoid liquid leakage and damage to the cabinet.

Water quality requirements: The coolant must use drinking water with corrosion inhibitors (such as ethylene glycol). Prohibit the use of water with chloride ion content>100 ppm or calcium carbonate content>160 ppm to prevent channel blockage or corrosion.

Chapter 3: Electrical Connections - Full Link Analysis from Power Supply to actuator

The correctness of electrical wiring directly determines the success or failure of replacement. This chapter will integrate the key wiring definitions scattered throughout the manual.

3.1 Power system connection

ServoOne adopts a design that separates the control power supply from the main power supply, which is conducive to parameter presetting first and then conducting strong power debugging.

Control power supply (24V DC):

Terminal: BG1-BG6a uses X9/X10; BG7 uses X44.

Specification: The voltage needs to be stable and filtered. BG1-BG4 allows ± 20% fluctuation, BG5-BG7 allows+20/-10%.

Starting current: The maximum starting current of BG1-BG4 can reach 6A (continuous 2A). When selecting a 24V power supply, the additional current consumption of motor brake and digital output must be considered (see Appendix Table A.15).

Main power supply (AC Mains):

Network type: It is allowed to be used in TN and TT networks (neutral grounded), but it is strictly prohibited to use it in IT networks (ungrounded), as single-phase grounding faults can cause voltage stress to double and damage insulation spacing.

Pre charging circuit (BG7 only): High power models (such as SO84.250-450) require an external pre charging circuit. The control sequence is as follows: close S1->close the pre charging contactor K2->when the DC bus voltage reaches the threshold ->close the internal relay contacts (X44/3,4) ->close the main contactor K1->disconnect K2, and the system is in standby mode.

3.2 Control signal and safety function wiring

The matching of digital signal interfaces is crucial when replacing security systems such as Honeywell.

STO safety torque shutdown:

Input terminals: ISDSH (X4/22) and ENPO (X4/10). Releasing STO requires both to be at a high level (≥ 18V) simultaneously. These two input terminals have OSSD capability and can be directly connected to the pulse signal of the safety relay.

Diagnostic output: RSH (X4/11, X4/12) provides STO status feedback for PLC monitoring.

Digital input/output:

Input: ISDO0-ISDO6 (X4/15-21). Input with Touch Probe function (such as ISDO4-ISDO6) can be used for high-speed position capture with a minimum internal delay of 2 μ s.

Output: OSD00 (X4/7) is a high-end output with a maximum current of 50mA and short circuit protection.

Attention: To avoid faults caused by "circulation", it is necessary to ensure that DGND (X4/1,13) does not form additional circuits with the equipment ground when wiring the signal lines.

3.3 Motor and Encoder Interface - Core Replacement Difficulties

When replacing motors or drivers, encoder matching is the most technically demanding step.

Encoder connection (X6, X7):

Resolver: Connect to X6 (9-pin D-sub socket). Table 3.15 in the manual provides detailed allocation of S1-S4 and excitation signals.

High resolution encoder (X7): supports multiple types, including:

SinCos with EnDat interface (Heidenhain)

SinCos with HIPERFACE ®  Interface (Sick Stegmann)

SSI Absolute Value Encoder

Power supply: The encoder power supply voltage can be selected from 5V (maximum 250mA) or 11V (maximum 100mA). A dedicated encoder cable with a "Sense" line (such as KGS2 KSxxx) must be used to compensate for the voltage drop transmitted over long lines.

Attention: Do not split the encoder cable to the terminal block adapter, as this will damage signal integrity.

Motor connection (X12):

Wiring: U, V, W three-phase output. Motor cables must use symmetrical cables with double-layer copper braided shielding layers (shielding density 60-70%).

Temperature sensor (PTC/KTY): connected to X5. The manual emphasizes that if PTC signals are transmitted through encoder cables (X6/5,9), there must be reinforced insulation between PTC and motor windings (in accordance with EN 61800-5-1).

3.4 Selection and Protection of Braking Resistors (RB)

Under regenerative power generation conditions, the braking resistor processes the feedback energy.

Built in resistors: BG1-BG4 optional built-in resistors. However, the manual warns that no energy input is allowed through the built-in resistor when operating continuously at rated AC current and maximum ambient temperature. Therefore, the built-in resistor is only suitable for occasional emergency shutdowns or scenarios where the driver load rate is below 80%.