LEGACY ELECTRICAL NON COMPLIANCE ISSUES
LEGACY ELECTRICAL NON COMPLIANCE ISSUES
(OP)
Recently our company had moved a piece of equipment from one location to another location, while installing and troubleshooting the electrical system I discovered what seem to be electrical safety non compliances. As a matter of ethics I believe the compliance issues should be fixed.
The control circuit for the MCR relays is 24VDC, the EPO loop back to the relays is run with the -24DC side of the ungrounded 24VDC power supply, in this case the power supplies all float, (no common ground from the -24VDC to earth), normally the -24VDC system supply is common grounded to earth and the EPO loop is +24VDC. This machine was built 9 years ago,the standards for safety controls were in place at that time still prevail, also there is no redundancy in either the EPO loop or in the MCR circuit.
This machine I know is at least a category 3 level machine,(it can cut fingers off). I have disclosed this to my supervisor and he has chosen to ignore it. What are the implications of letting this go, and is this somehow an accepted methed for an EPO circuit 9 years ago.
The control circuit for the MCR relays is 24VDC, the EPO loop back to the relays is run with the -24DC side of the ungrounded 24VDC power supply, in this case the power supplies all float, (no common ground from the -24VDC to earth), normally the -24VDC system supply is common grounded to earth and the EPO loop is +24VDC. This machine was built 9 years ago,the standards for safety controls were in place at that time still prevail, also there is no redundancy in either the EPO loop or in the MCR circuit.
This machine I know is at least a category 3 level machine,(it can cut fingers off). I have disclosed this to my supervisor and he has chosen to ignore it. What are the implications of letting this go, and is this somehow an accepted methed for an EPO circuit 9 years ago.





RE: LEGACY ELECTRICAL NON COMPLIANCE ISSUES
Would the current circuit continue to function when subjected to radiated and conducted emissions, line surges and sags, or ESD pulses? Is there any reason why either supply rail of this 24V supply would present a shock hazard? It would either have to be accessible or capable of energizing the machine chassis to shock someone. Is there enough power available from it to constitute a fire hazard under any load? Is there overload protection in the form of fusing or other means?
RE: LEGACY ELECTRICAL NON COMPLIANCE ISSUES
The fact that the EPO circuit is not grounded should not effect the compliance of the system if the system has been designed this way. (if the ground has lifted then it is a circuit fault which should be fixed accordingly). Be aware, some circuits rely on a floating supply in order to detect faults.
RE: LEGACY ELECTRICAL NON COMPLIANCE ISSUES