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  1. Paulpower

    Power factor of 3MW Induction Motor

    Hello everyone, Generally, PF of induction motor rated 50KW or below is 0.8 - 0.85, but can I specify the PF of a 2MW - 3MW induction motor as 0.9 or higher? Does any manufacturer catalogue cover this information? Thanks, Paulpower
  2. Paulpower

    Outdoor Wiring of Fire Alarm System

    Hi Stookeyfpe, The small building is a separate indoor unit substation.It is not protected by automatic sprinkler system. The corridor is totally enclosed as an indoor sturcture and it is protected by an automatic sprinkler system. The project is in Canada. Paulpower
  3. Paulpower

    Outdoor Wiring of Fire Alarm System

    Hello, everyone, I am working on a fire alarm system that protects a building and a long corridor. The building and corridor are 20m apart. The fire alarm panel is located in the building. We have to run twisted SLC wires, notifications appliances circuits wires and optical fiber cables in the...
  4. Paulpower

    AN/AF Dry type transformer secondary fault level

    Thanks, davidbeach. I will ask manufacturer to provide impedance data at AF rating and compare two results at different rating. If the calculated fault level is 60KA, can I specify the CB interrupting capacity at 65KA or shall I specify the capacity at 85KA or 100KA for redundancy?
  5. Paulpower

    AN/AF Dry type transformer secondary fault level

    Dear all, Dry type transformer usually has two capacity AN and AF. For example, 1MVA and 1.5MVA with fan operating. When we calculate the secondary short circuit current, what capacity should be used? 1MVA or 1.5MVA? Is there any relevent document? Thanks, Paulpower
  6. Paulpower

    Ground Grid outside or inside building?

    I work on a project near Arctic circle. Because of high resistivity of permafrost, some engineers suggest that ground profile be laid inside building below grade. However, the electrodes are still buried outside the building. Grounding resistance mainly depends on the number, size, length of...
  7. Paulpower

    Should 15KV system ground be connected to 280v ground

    Hi Marmite, Thanks for your detail explanation. We can not earth the neutral at service termination because we have ground fault protecion by zero sequence CT at 208v bus which is required by CODE. We plan to run a separate bare copper cable from the substation neutral to the building as...
  8. Paulpower

    Should 15KV system ground be connected to 280v ground

    Hi, I am working on a substation project. The transformer is 13.8kv/208v DYn1, secondary solidly grounded. The primary is tapped from 13.8kv overhead line. 13.8kv system is high resistance grounded system.We have ground grid installed around the substation building. Metal clad Substation ground...
  9. Paulpower

    how many cables can be fed by a 42-way panel?

    There are about 40 circuits of 120V single phase loads which are fed by a common 42 way panelboards. The loads are lighting and HVAC units. If I use 40 cables separately with glands, there are not 40 knockouts on the panel and cables are crowded on the panel surface. How many cables can a panel...
  10. Paulpower

    15KV and 1KV cable termination Specification

    Can anyone help me with the following? For a metal-clad unit substation, incoming line are 15KV 2/0 cable from O/H line, feeder cables are 4 run of 4c300MCM 1KV cables, both are bottom entry. How to specify the cable termination? oudoor on the O/H pole and indoor in the switchgear. Cable boot...

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