OhioAviator
Electrical
- Sep 8, 2003
- 123
Hello Everyone,
I am in the process of designing a 480V three-phase, 3-Wire + Ground industrial distribution system that will be fed from a 2500 KVA pad mount transformer with a 480V Delta secondary (The delta secondary is being used to create a 30 degree phase shift from a different pad mount transformer with a wye secondary). The ground reference on the delta transformer will be created by connecting a zig-zag grounding transformer and a continuously rated 50A Neutral Grounding Resistor. A ground fault monitoring system will be used in conjunction with the NGR to create a 'Ground Fault' Alarm for the plant to use to create a controlled shutdown scheme. Our intent is to connect the zig-zag directly to the secondary of the pad mount transformer with NO switching or overcurrent devices of any kind between the pad mount transformer and the zig-zag. However, it's been brought up by a team member that NEC Article 450.5 requires overcurrent protection for the zig-zag transformer, which I have never done in the past.
Question: Is overcurrent protection required between the pad mount transformer secondary and the zig-zag transformer?
Thanks in advance for your advice and assistance.
J.R.
Galatians 2:20
I am in the process of designing a 480V three-phase, 3-Wire + Ground industrial distribution system that will be fed from a 2500 KVA pad mount transformer with a 480V Delta secondary (The delta secondary is being used to create a 30 degree phase shift from a different pad mount transformer with a wye secondary). The ground reference on the delta transformer will be created by connecting a zig-zag grounding transformer and a continuously rated 50A Neutral Grounding Resistor. A ground fault monitoring system will be used in conjunction with the NGR to create a 'Ground Fault' Alarm for the plant to use to create a controlled shutdown scheme. Our intent is to connect the zig-zag directly to the secondary of the pad mount transformer with NO switching or overcurrent devices of any kind between the pad mount transformer and the zig-zag. However, it's been brought up by a team member that NEC Article 450.5 requires overcurrent protection for the zig-zag transformer, which I have never done in the past.
Question: Is overcurrent protection required between the pad mount transformer secondary and the zig-zag transformer?
Thanks in advance for your advice and assistance.
J.R.
Galatians 2:20