I have a concern, refer to the picture, The switch-3, which remains a single point of failure which is connected to the ET-200SP of 8 Nos of pumps
but switch-3 manufacturer confirms that the MTBF is higher than 46 years.
Now there is a solution to this with MRP ring topology as below, with Switch 3 removed.
What are your opinions on Option 1 Vs Option 2?
Motor size: 2.7 MW @ 675 V, fed from a VFD.
External cable arrangement: 15 runs of 3C x 95 mm² cables, giving a total phase conductor cross sectional area of 1425 mm².
According to IEC 60034-1, For other cross-sectional areas of phase conductors, the earthing or protective conductor shall have a cross-sectional area at least equivalent to:
– that of the phase conductor for cross-sectional areas less than 25 mm2;
– 25 mm2 for cross-sectional areas between 25 mm2 and 50 mm2;
– 50 % of that of the phase conductor for cross-sectional areas exceeding 50 mm2.
Does this mean the motor manufacturer is required to provide an earth/bonding conductor with a cross-sectional area of at least 712.5 mm²?
We need to provide continuous monitoring of the stator field winding insulation while the generator is offline. Would it be feasible to use this Bender module for that purpose? Also, would the three single-phase VTs (wye-grounded to wye-grounded) interfere with the operation of the Bender module?
If an equipment, such as a switchgear lineup, has already been certified by ABS and the manufacturer later modifies the approved design (for example, by removing some cubicles from the lineup), will the switchgear need to be recertified by ABS?
I have a similar question regarding the electrical layout. After receiving ABS approval, if equipment is added, removed, or relocated within the layout, does the revised layout require recertification by ABS?
So we have a Thruster motor VFD which has the df/dt filter in the VFD output side.
- Its a part of VFD panel at the output side
- The Motor voltage is of 675V
- Which standard to be followed? (IEC 60076-6, IEC 61558-2-20 or IEC 61378)
- This is from a chinese manufacturer
- obviously no rating plate, on asking, the chinese put a nameplate but again no standard on it
- We asked for test certificates obviously they produced some fake certificates
- on further enquiry, they say the entire VFD is certified by ABS, so we need not bother about the internal component
Case closed. Do you agree? what are your opinions? Similar thing for other important components inside this VFD
This is a star delta starter. The rectangular marked is a busbar tapped from the main busbar connecting to the main circuit breaker, which feeds the star delta contactors below
Would this be considered Form 3b according to IEC 61439?
To me, it appears to be Form 2b. Do you have any suggestions on how it could be modified to achieve Form 3b?
I'm not the manufacturer or Designer; just received a picture from a chinese manufacturer.
What is the voltage drop allowed for EDG starting cranking motor from the batteries to the cranking motor?
From ABS MVR: section 4-8-4: clause, 21.5 - Cable Voltage Drop
For supplies from batteries with a voltage not exceeding 50 V this limit can be increased to 10%.
From ABS MVR: section 4-8-2: clause, 5.9.2 - Accumulator Battery
Carrying the emergency electrical load without recharging while maintaining the voltage of the battery throughout the discharge period within 12% above or below its nominal voltage.
Which one to follow?
(or)
The cable to be sized including the starter motor inrush current, to demonstrate that the starter motor can start the engine reliably when the battery is discharged to 80% (worst case).
There is a measuring panel on both Bus-A and Bus-B which has its respective VT's with a broken delta connection is provided at the secondary side of the VT and each measuring panel has its respective IED. The bus tie also has an IED.
Currently, the broken delta is connected to the respective IEDs in the measuring panels, and the output from the IED is used to trip the bus tie.
Have any opinions on this arrangement?
What are the typical signal exchanges between the AVR, IED (protection relay) and the circuit breaker for Generator applications? (for Diesel generators above 1000kW in marine applications)
The size of the internal earth bus (the bar running through the entire switchgear lineup) in my current project differs from the size indicated in the type test report. Is this acceptable? Is the busbar size specified in the type test report applicable only to the main busbars, and not to the earth bus? If the manufacturer provides calculations demonstrating that the earth bus size is adequate for the specified fault current and duration, would this be considered acceptable? For example, if the short-time withstand current/duration is 25 kA for 1 second, and the adiabatic equation indicates a required conductor size of approximately 175 sq.mm, would providing a 200 sq.mm earth bus (40 × 5 mm) be acceptable in this case?
Can the branch earth bar size be different from the main earth bar? In the type test certificate provided by the manufacturer, the same earth bar size was used for both the main earth bar and the branch earth bar.
This is from Siemens Siprotec 7UM85 Generator protection relay with Synchronizer function.
What is the meaning of Deenergized switch, Asychronous operation mode, Synchronous operation mode here?
Electrical machines - I understand the concept of temperature rise in windings, but I’m unsure about the temperature rise in a generator’s cooling system. There are two key temperatures involved: the cooling fluid’s inlet and outlet temperatures. The difference between them is the temperature rise of the coolant.
My understanding is that if this temperature difference is large, it means the cooling effect is higher, and if the temperature difference is small, the cooling is less effective.
The specification states that a minimum temperature rise of 10K is required for the cooling fluid, but the vendor's datasheet shows a coolant temperature rise of 15K. Based on this, the 15K provided by the vendor should be better than the 10K specified, Is my understanding correct?
Additionally, I’ve noticed some motor specifications that limit the cooling water outlet temperature to a value like 37°C, and also restrict the coolant temperature rise to a certain level, like 7K.
Why do the specs limit the cooling water outlet temperature, and why do they restrict the temperature rise to specific values like 7K?
Generators / Motors - I understand the concept of temperature rise in windings, but I’m unsure about the temperature rise in a generator’s cooling system. There are two key temperatures involved: the cooling fluid’s inlet and outlet temperatures. The difference between them is the temperature rise of the coolant.
My understanding is that if this temperature difference is large, it means the cooling effect is higher, and if the temperature difference is small, the cooling is less effective.
The specification states that a minimum temperature rise of 10K is required for the cooling fluid, but the vendor's datasheet shows a coolant temperature rise of 15K. Based on this, the 15K provided by the vendor should be better than the 10K specified, Is my understanding correct?
Additionally, I’ve noticed some motor specifications that limit the cooling water outlet temperature to a value like 37°C, and also restrict the coolant temperature rise to a certain level, like 7K.
Why do the specs limit the cooling water outlet temperature, and why do they restrict the temperature rise to specific values like 7K?
The below are the signals / interlocks I would consider to close on to the dead bus,
No VT MCB trip
Voltage not in DEAD zone
No Lock out trips
All other feeder breakers (No back feeding breakers) from the bus are opened.
Any suggestions/ add ons to consider?
Can someone suggest me a correct ferrule for this one? The cables with small cross section is terminated by the manufacturer. The bigger cables are the external cables to be terminated
Can someone suggest me a correct ferrule for this one? The cables with small cross section is terminated by the manufacturer. The bigger cables are the external cables to be terminated
Why the left one is just considered as SIL 1 and the right one is considered as SIL 3 (with just adding 2 sensors (NC)? what are those sensors with NC contact?
Which standards define the protection setting criteria for medium voltage diesel engine generators rated below 10 MW (Shipboard generators), or anywhere can I find this information?
Which standards define the protection setting criteria for medium voltage diesel engine generators rated below 10 MW (Shipboard generators), or anywhere can I find this information?
