Agilent Technologies L4400 manual General Purpose Switch Instrument, Wa Rn I N G

6L4437A General Purpose Switch

General Purpose Switch Instrument

The L4437A General Purpose (GP) switch can be used to route signals or control other system devices.

•The L4437A provides independent control of 32 latching relays:

•Twenty- eight Form C relays rated for 1 A at 60 W per channel

•Four Form A relays rated for 5 A at 150 W per channel.

The L4437A contains armature- latching relays, and you can use the switch for device actuation, digital output, or combine it with additional switch instruments to create flexible switching topologies. You can close multiple channels at the same time. The L4437A does not implement an analog bus.

A temperature sensor on the instrument triggers system interrupts when high- carry current- induced heat on the instrument is excessive. This over- temperature situation generates an SRQ event when the factory- set 70 oC threshold is reached. It is up to the user to determine what, if any, action should be taken.

Reactive loads (those that include significant inductance or capacitance) can cause voltage spikes or current spikes during switching operations. The L4437A is designed for switching reactive loads. The optional 34937T terminal block has solder pads for adding snubber circuits for the 5 A relays to reduce the reactive transients. See the drawings on page 134 for the locations of snubber circuit pads and installation information about a snubber circuit.

A hardware jumper on the L4437A allows you to define the power- failure states for the instrument’s 5 A latching relays. Depending on the position of the jumper, the 5 A relays will either open or maintain state when system power failure occurs. When shipped from the factory, the power- fail jumper is in “MAINTAIN” position (all relays maintain their present state when power fails).

WA RN I N G	Before changing the position of the jumper, turn off the instrument
	and remove all external connections. Wait five to ten seconds to
	allow the instrument’s internal capacitors to discharge.

Remove the L4437A instrument sub- assembly from the instrument carrier and then remove the sheet metal cover from the sub- assembly. Move the position of the jumper mounted on the sub- assembly. See the figure below for the jumper’s location.

128 L4400 User’s Guide