Service manual

Table 4-1. E1355A/E1356A Relay Functions
Relay Function Notes
K100
K101
K102
K103
Measure strain (channel 00)
Measure strain (channel 01)
Measure strain (channel 02)
Measure strain (channel 03)
All strain gage measurements are made via the
K90 relay connected to a multimeter
K108
K109
K110
K111
Measure strain (channel 04)
Measure strain (channel 05)
Measure strain (channel 06)
Measure strain (channel 07)
All strain gage measurements are made via the
K90 relay when connected to a multimeter
K104
K105
Measure lead wire resistance (channel 08)
Measure lead wire resistance (channel 09)
This measurement increases accuracy of strain
gage measurements by canceling effects of lead
wire resistance.
K106
K107
Measure voltage across 1KΩ bridge (channel 10)
Measure voltage across 1KΩ bridge (channel 11)
These measurements check stability and condition
of the resistor pack RP1.
K112
k113
K114
K115
Shunt verification test (channel 12)
Shunt verification test (channel 13)
Measure guard voltage (Vg) (channel 14)
Measure bridge excitation voltage (+Vs) (chan 15)
Simulates known value of compression
Simulates known value of tension
Made with respect to the excitation voltage (-Vs)
K90
K91
K93
Strain gage measurements
I+ source
+Vs, -Vs excitation voltage
Terminal Module
Description
The terminal module contains the set of bridge resistors used in strain gage
measurements. The two 1kΩ bridge resistors contained in the resistor pack
(RP1) make up one half of the bridge arrangement. The other half of the
bridge arrangement for channel 0 consists of a user-supplied 120Ω strain
gage and the 120Ω resistor R0.
The junction (Vg) between the resistors R21 and R20 is known as a Wagner
Ground. The purpose of the Wagner Ground is to reduce stray leakage
currents when the Guard lead (G) is connected to the specimen being
measured.
Chapter 4 Service 55