Hazards associated with electrical systems are the most common in the Hall C environment. Almost every subsystem requires AC and/or DC power. Due to the high current and/or high voltage requirements of many of these subsystems the power supplies are potentially lethal.
Aside from the resetting of circuit breakers you should not attempt to solve any problems associated with AC power distribution without consulting responsible personnel.
Anyone working on AC power in Hall C must be familiar with the EH&S manual and must contact one of the responsible personnel.
The remote control systems to operate the the cryotarget lifter, the Møller detector collimators and the HMS and SOS collimator boxes are all located at the back side of the SOS power supplies (close to the entrance door to Hall C). Regular operation occurs through RS232 (or RS485) communication with the respective stepper-motors or BDS5 motors/actuators. Brake cables are added to prevent vertical ladders from falling in case of a power loss. All systems are equipped with emergency buttons.
The Hall C detectors in general require High Voltage, up to 3000 Volts, drawing currents up to a few mA. These voltages are typically provided by a CAEN SY403 high voltage supplies, which can deliver up to 3000 Volts at up to 3 mA current per channel. In rare cases (beam losses monitors, neutron detectors) the voltages are provided by LeCroy 1450 high voltage supply, with similar voltages and currents per channel. The following detector systems require this kind of voltages:
Note that in addition the cold cathode gauges which are used to measure the pressure in the spectrometers and/or beam line utilize high voltage!
Several safety measures are taken to prevent the voltage divider bases from becoming sources of ignition:
Most of the electronics require DC power. These DC voltages are provided by the power supplies of the crates in which the modules sit. There are 8 powered NIM crates, each with a power supply that requires 115 VAC input and provides approximately 200 Watts of power on +/- 6, 12, and 24 VDC output lines. There are 4 CAMAC crates which also require 115 VAC input, and provide a maximum of 400-500 Watts. There are also 3 VME crates, whose power supplies provide approximately 500 W. These all run off of clean power, which is provided from power strips installed in the racks, and use standard power cords.
There are also 2 Fastbus crates which require 208 VAC input, and can provide a maximum power output of roughly 4000 W. While the NIM, CAMAC, and VME crates contain their own power supplies and are therfore fairly well protected, the Fastbus power supply is separate from the crate and does not provide intrinsic protection for the power leads and connections. Extra precautions must be taken to use these crates safety. There will be shields installed over the back of the fastbus power supply to prevent contact with the power leads. The racks in which they are mounted have rear doors that will be closed at all times when the Fastbus power supply is on.