M
Michael4444
Guest
Very often during our Field Work we find GFI Relays set at their Minimum (Amps) Pick-Up value. This could lead to Nuisance Tripping.
On other instances, we have seen the GF Relays set at Max (1200 A ), which, depending on the actual electrical load at the Facility, may in fact Defeat the purpose of the GF Relay.
We must remember that GFI protection has One Main Purpose in life, and that is to protect Plant Personnel from the results of Catastrophic Fire. The Protection of ancillary equipment and the Facility in general is Secondary in nature to that of saving a life or to keep someone from suffering personal Injury
It is very important to set the GFI Relay to a proper value, as dictated by the Electrical Load at the particular Facility.
Ideally, a recent or updated Coordination Study exists on File; however more often than not, this is not the case.
If we are working with insufficient infromation, in order to advice the client properly, we must make a definitive, accurate decision for choosing a proper Pick-up value on the GFI .
Ths Pick-Up setting Value is never a "Guess" but rather should always comprise of a conservative estimate based on the most recent existing Electrical Load Data at the Particular location.
This value must be low enough so as to Not cause a GFI Defeat Condition; and yet High enough not to cause Nuisance tripping of the Ground Fault Relay.
In our experience, when setting the Pick-Up function on a Facility's Main Circuit Interrupter Device's GFI Relay, and where no coordination study exists, a conservative value is to set the Pick-Up at 20% of existing maximum electrical load at the particular Facility..
If that specific 20% value is not one of the Fixed Ranges available at the GFI Relay Control Module, go UP to the next available Fixed Range Value.
For example, let us assume that the Max Load is 800 Amps. Ideally, the GFI Pick-Up should be set at 160 Amps. But the control Module settings are 100, 200, 300, --> 1200 Amps..
In our example, we would set the GFI Relay Pick-Up at 200 Amps.
Time Delay, if present as an available Function, would be set at Minimum. NOT Instantaneous, but Minimum.
This Time Delay setting is adequate in order to compensate for our expanded Ampere Range setting with a faster Time Delay response.
Again, a 20% calculation based on a Facility's actual Max Load for setting the GFI Value Range is a conservative value which will protect personnel and equipment adequately, yet will not be likely to cause unnecessary Tripping of the Main Circuit Interruptor...
Have a Happy Ground-Fault Day..
On other instances, we have seen the GF Relays set at Max (1200 A ), which, depending on the actual electrical load at the Facility, may in fact Defeat the purpose of the GF Relay.
We must remember that GFI protection has One Main Purpose in life, and that is to protect Plant Personnel from the results of Catastrophic Fire. The Protection of ancillary equipment and the Facility in general is Secondary in nature to that of saving a life or to keep someone from suffering personal Injury
It is very important to set the GFI Relay to a proper value, as dictated by the Electrical Load at the particular Facility.
Ideally, a recent or updated Coordination Study exists on File; however more often than not, this is not the case.
If we are working with insufficient infromation, in order to advice the client properly, we must make a definitive, accurate decision for choosing a proper Pick-up value on the GFI .
Ths Pick-Up setting Value is never a "Guess" but rather should always comprise of a conservative estimate based on the most recent existing Electrical Load Data at the Particular location.
This value must be low enough so as to Not cause a GFI Defeat Condition; and yet High enough not to cause Nuisance tripping of the Ground Fault Relay.
In our experience, when setting the Pick-Up function on a Facility's Main Circuit Interrupter Device's GFI Relay, and where no coordination study exists, a conservative value is to set the Pick-Up at 20% of existing maximum electrical load at the particular Facility..
If that specific 20% value is not one of the Fixed Ranges available at the GFI Relay Control Module, go UP to the next available Fixed Range Value.
For example, let us assume that the Max Load is 800 Amps. Ideally, the GFI Pick-Up should be set at 160 Amps. But the control Module settings are 100, 200, 300, --> 1200 Amps..
In our example, we would set the GFI Relay Pick-Up at 200 Amps.
Time Delay, if present as an available Function, would be set at Minimum. NOT Instantaneous, but Minimum.
This Time Delay setting is adequate in order to compensate for our expanded Ampere Range setting with a faster Time Delay response.
Again, a 20% calculation based on a Facility's actual Max Load for setting the GFI Value Range is a conservative value which will protect personnel and equipment adequately, yet will not be likely to cause unnecessary Tripping of the Main Circuit Interruptor...
Have a Happy Ground-Fault Day..