A control system (100, 200, 300) for maintaining a production fluid flow during proof testing of a High Integrity Protection System, i.e., "HIPS", the control system comprising: a HIPS (102, 202, 302) comprising: a first pressure sensor (114, 116, 118, 214, 216, 218, 308, 310, 312) operable to sense a fluid pressure of the production fluid flow; a first circuit breaker (120, 122, 220, 222, 314, 316) operable selectively to open to prevent a flow of electrical power along the first electrical path or close to permit the flow of electrical power along the first electrical path; and a first data processor (112, 212, 306), the data processor operable to: receive a first pressure signal from the first pressure sensor, the pressure signal indicative of a fluid pressure of a production fluid flow; compare the received first pressure signal to a predetermined fluid pressure to determine the presence of an overpressure condition of the production fluid flow; and open the first circuit breaker to discontinue the production fluid flow if the received first pressure signal meets or exceeds the predetermined fluid pressure; and an auxiliary system (104, 204, 304) comprising a second circuit breaker (134, 136, 234, 328) arranged in a bypass (135, 137, 235, 332) of the first electrical path, the second circuit breaker operable selectively to open to prevent a flow of electrical power along the bypass and close to permit the flow of electrical power along the bypass, the auxiliary system operable to close the second circuit breaker prior to the first circuit breaker being opened by the first data processor in response to a test pressure signal received by the first data processor from the first pressure sensor during the proof test. a HIPS (102, 202, 302) comprising: a first pressure sensor (114, 116, 118, 214, 216, 218, 308, 310, 312) operable to sense a fluid pressure of the production fluid flow; a first circuit breaker (120, 122, 220, 222, 314, 316) operable selectively to open to prevent a flow of electrical power along the first electrical path or close to permit the flow of electrical power along the first electrical path; and a first data processor (112, 212, 306), the data processor operable to: receive a first pressure signal from the first pressure sensor, the pressure signal indicative of a fluid pressure of a production fluid flow; compare the received first pressure signal to a predetermined fluid pressure to determine the presence of an overpressure condition of the production fluid flow; and open the first circuit breaker to discontinue the production fluid flow if the received first pressure signal meets or exceeds the predetermined fluid pressure; and a first pressure sensor (114, 116, 118, 214, 216, 218, 308, 310, 312) operable to sense a fluid pressure of the production fluid flow; a first circuit breaker (120, 122, 220, 222, 314, 316) operable selectively to open to prevent a flow of electrical power along the first electrical path or close to permit the flow of electrical power along the first electrical path; and a first data processor (112, 212, 306), the data processor operable to: receive a first pressure signal from the first pressure sensor, the pressure signal indicative of a fluid pressure of a production fluid flow; compare the received first pressure signal to a predetermined fluid pressure to determine the presence of an overpressure condition of the production fluid flow; and open the first circuit breaker to discontinue the production fluid flow if the received first pressure signal meets or exceeds the predetermined fluid pressure; and receive a first pressure signal from the first pressure sensor, the pressure signal indicative of a fluid pressure of a production fluid flow; compare the received first pressure signal to a predetermined fluid pressure to determine the presence of an overpressure condition of the production fluid flow; and open the first circuit breaker to discontinue the production fluid flow if the received first pressure signal meets or exceeds the predetermined fluid pressure; and an auxiliary system (104, 204, 304) comprising a second circuit breaker (134, 136, 234, 328) arranged in a bypass (135, 137, 235, 332) of the first electrical path, the second circuit breaker operable selectively to open to prevent a flow of electrical power along the bypass and close to permit the flow of electrical power along the bypass, the auxiliary system operable to close the second circuit breaker prior to the first circuit breaker being opened by the first data processor in response to a test pressure signal received by the first data processor from the first pressure sensor during the proof test.