Well now I am confused (again). Since the calculation does not take into consideration that the switchgear doors are closed or open, do I consider all tasks as if they are performed on energized and exposed equipment?
This would mean that the switchgear could not even be approached without PPE...
The NFPA 70E only requres a level 0 PPE around metal clad switchgear (with doors closed).
I like the arc-detection suggestion by stevenal. This definitely reduces the PPE requirements if the upstream device has a fast operate time. And thanks for the tip on using a flash!
The response from NFPA is that 70E does not address arc-resistant switchgear, and as such, there is no reduction in PPE requirements with the use of arc-resistant gear.
Obviously arc-resistant gear increases worker safety, but I do not see an incentive for the significant increase in cost if...
Following reply is from are-resistant switchgear manufacturer: "Since arc resistant switchgear (not only ABB's but any manufacturer's) is intended to control the explosion from an arc event, and not to reduce the amount of incident energy, the standards do not state that the level of PPE can be...
Zogzog - If the switchgear is arc-resistant and the doors are closed, can I assume that the arc flash hazard is eliminated and PPE is not required. For example: from table 130.7(C)(9)(a)of 70E, CB or fused switch operation > 1kV with doors closed requires a PPE level 2. Does arc-resistant gear...
Can someone please tell me where I can find information on arc-resistant switchgear and it's impact on PPE requirements (if any)? NFPA 70E-2004 does not appear to address arc-resistant design of switchgear. Evidently this design does not reduce the Hazard/Risk Category per NFPA.
-electricpete, if I increase the starting torque, the motor should reach running speed sooner. As you stated in a previous post; perhaps the trip is occuring during the transition to full line voltage. (It is a timed transition).
Thank you all for your input.
-jbartos, I'm using an AEMC MX54 DMM, with clamp-on probe MR461 rated to 600A.
I have verified that the pumps are not being motored prior to starting.
An interesting specification on the Siemens magnetic trip breakers, their range is -20/+30%! So, at 1100A setting...
I should have mentioned that the problem has only recently occured and is intermittent.
The installation has been in service for approximately 3 years without the reported problem.
Regarding Q3, it gets more complex, motor1 trip is set at 1100 Amps, and motor2 trip is set at 2500 Amps! Needless...
We are experiencing instantaneous magnetic breaker trips (1100 Amp setting) when transfering between normal and backup hydraulic systems. The system consists of two 60hp, 460V, 71FLA, Induction motors (Design type B). Each motor runs it's own hydraulic pump to a common hyd system. Each motor has...
What benefit is there to performing speed control via PLC when an off-the-shelf speed-governor can be purchased with desired PID characteristics? Wouldn't it be practical (& economical) to simply bias an existing speed-governor?
