Agilent Technologies L4400 manual Safety Interlock, High Energy Sources

Operating and Programming 3

The lightning- caused transient overvoltages that may occasionally occur on mains power outlets may be as high as 2500 Vpeak.

WARNING	Do not connect the Analog Buses directly to a mains power outlet.
	If it is necessary to measure a mains voltage or any circuit where a
	large inductive load may be switched, you must add signal conditioning
	elements to reduce the potential transients before they reach the
	Analog Buses.

High Energy Sources

The Analog Buses are designed to handle inputs up to their rated currents or their rated powers, whichever is less. Under certain fault conditions, high energy sources could provide substantially more current or power than the instrument can handle. It is important to provide external current limiting, such as fuses, if the inputs are connected to high- energy sources.

CAUTION	Install current limiting devices between high energy sources and the
	module inputs.

Safety Interlock

The Safety Interlock feature prevents connections to the Analog Buses if no terminal block or properly- wired cable is connected to the L4421A or L4433A.

Normally, if you attempt to connect to the Analog Buses without a terminal block or properly- wired cable connected, an error is generated. You can, however, temporarily disable errors generated by the Safety Interlock feature. This simulation mode may be useful during test system development when you may not have connected any terminal blocks or cables to your module.

CAUTION	The Safety Interlock feature is implemented in hardware on the modules
	and cannot be circumvented. Regardless of whether the simulation mode
	is enabled or disabled, all Analog Bus operations are prohibited as long as
	no terminal block or properly-wired cable is connected to the module.

•When the simulation mode is enabled, the Analog Bus relays will appear to close and open as directed. For example, no errors are generated if you close an Analog Bus relay from the remote interface or Web Interface. However, remember that the Safety Interlock feature prevents the actual hardware state of the Analog Bus relays from being changed. When you connect a terminal block or cable to the module, the Analog Bus relays will open and close normally.

L4400 User’s Guide 67