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  • Users: roydm
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  1. roydm

    Impedance Heating Power Control

    I'm fairly familiar with using Zero crossover SCR controls for large resistive heating loads but what is the best method of controlling a transformer supplied heat load, I seem to recall that the transformer should be phase angle controlled. I am looking at 400 - 500 KW load. Thanks in advance.
  2. roydm

    Tesla Motors

    Just out of curiosity is there anything special about the motors in a Tesla automobile. I know they are known for their lightning acceleration. What type of motor? 3 Phase or more? How many Poles? Rev range? Voltage? Horsepower? Any other interesting details on the drive system? My SIL is very...
  3. roydm

    Remote Engine Control

    I often see trains of 100 cars or more passing by my window, usually they have 2 or more engines in front but often they have an engine in the middle about 50 cars back or right at the rear. What is the method of controlling the remote engines, it seems that a wire connection would be...
  4. roydm

    Basler Voltage Regulator

    I have been given a couple of 1971 vintage Basler Electric Volts per Cycle Regulators to fix P# 9085300100 As far as I can tell the tapped Toroid Reactor on one is u/s at least it has wildly different Ohms readings from the identical unit on the other making me think there may be a short between...
  5. roydm

    ACS550 Parameters

    We have a 460V, 60Hz, 1775RPM, 75HP motor connected to a positive displacement pump. The VFD is ABB, I'm hoping there is an expert on these drives. If the pump stops under load the discharge pressure is maintained by a check valve. On restart the motor is unable to pull away under pressure, I...
  6. roydm

    Soldering Surface Mount Components

    I know most boards are now put together by robot but is there an elegant way to solder surface mount components by hand? Special solder or flux? I'm just referring to chips with a low connection count, typical 3 maximum of 8 Thanks Roy
  7. roydm

    Interesting old Motor

    Over the weekend I passed through Greenwood BC, there in a park was an ancient Ingersol Rand No 10 compressor hooked to a 3 phase alternator. At first I thought the compressor was a steam engine since it had mechanically activated valves. The electrical machine was a wound rotor with large solid...
  8. roydm

    Comparator Help Please

    Hi, I'm trying to design a simple delay circuit for a Peizo Electric buzzer to be used on a 24 VDC vehicle, I bought 30 of these LM211-N Comparators thinking they would be up to the task. On the data sheet it says the output is good for 50 mA but I don't seem to be able to get it to pull up...
  9. roydm

    Voltage drop across slipring brushes

    Hi, I ride old motorcycles one of which has a Bosch alternator 3 phase wound rotor type similar to most older cars. For some treason I am seeing excessive Voltage drop across the positive slipring brush ~700mV while the other ring is less than 300 this is enough to significantly reduce the...
  10. roydm

    Measuring Voltage in Extremly Noisy Environment

    Hi, I have an application where I need to measure battery Voltage in a noisy (RFI switching regulator) environment. I need a significant number of transducers 0 - 150 VDC sending data to an AB PLC. It's pretty hard to shield the transducers since they need to be connected to the same cables that...
  11. roydm

    Voltage Measurement in Noisy Environment

    Hi, I am working on a large storage battery where I need to measure the voltage of individual batteries. Associated with the storage is a large bi-directional inverter which is extremely noisy (RFI) I need to measure individual battery Voltages around 100 Volts. Past experience tells me that...
  12. roydm

    Foundation Fieldbus - Is there a range?

    We are all used to setting the 4-20 mA output range of a transmitter. I purchase lots of fieldbus transmitters but unfortunately don't get to play with them in the field Example: I have a pressure transmitter with a cell capable of measuring 0 - 100 psi I only need to measure up to 50 psi I...
  13. roydm

    Capacitor marking, can someone explain it?

    Hi, I have a number of 120 VAC output circuit boards Near the output thyristor is a small surface mount device, it looks to me like a capacitor, several of these are damaged the device is marked as below ----R+---- 475 50k 906 If someone could tell me what all this means I would be...
  14. roydm

    Labview Address Scheme

    Labview Project Hi, I have a small project, 5 x 8 slot racks of Labview I/O with a cRIO 19025 controller. I won't be doing the configuration but I would like to understand how the addressing works for my drawings I think the module slots start at zero thru 7 Do the racks also start at zero or...
  15. roydm

    Blower High Current Draw

    I have another question for the motor gurus. At a project in Korea we have 3 blowers that seem to be drawing very high current The motors are 460 Volt 53 kW with a nameplate FLA of 77 Amps coupled to the blowers by belt drive The speed has been checked with a tacho, both motor and blower are as...
  16. roydm

    Help with Motor Connection

    A colleague has asked me to help figure out the wiring of a 2 speed single phase motor I spent a couple of hours searching the web but unable to find any information on the wiring, It's a GE model 5KCP19 SG400 208 - 220 Volt 50 / 60 Hz XGU 2 / 6 pole 3.8 / 2.4 Amps Time rating INTMT Class B...
  17. roydm

    VFD Current Imbalance

    We have a client who installed 2 149kW motors and VFDs using regular cable and no reactors. The cables are typically 250 - 300 meters long (VFD to motor). We are seeing current difference between phases of 5 - 7% Assuming the motors are ok (all new) the only thing I can attribute this...
  18. roydm

    Interpreting Thermistor Tables

    I am trying to substitute a thermistor which gives me resistance values in steps of 10 Ohms from zero to 100. 0=9750. 10=5970, 20=3747 - - - - - -100=204 Ohms When I look at the thermocouple parts lists they rate the devices in a totally different fashion Rt/R25 (related to 25°C and use some...
  19. roydm

    Cuttler Hammer Circuit Cards

    Cuttler Hammer Diagram Hi, I have a bunch of obsolete CH D120PM20 circuit cards to repair I tried to find a diagram on the www but couldn't find anything. If anyone has information on these i would be most appreciative. Thanks Roy
  20. roydm

    Hazardous Location Protection Method

    We do a lot of work overseas and often get into a bun fight over the requirements for Hazardous location requirements. For example pump motors in Class 1 Div 2 Group IIB the client often expects us to provide a motor with Ex d (explosion proof) certification where it only needs to be Ex nA (non...

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