Trifitek TR-79, Руководство пользователя, Страница: 34 / 46

11
2. When using Capacitance function, discharge capacitor(s) before making any
measurements. Large value capacitors should be discharged through an appropriate
resistance load
DC

A Current function
Inputs are made through the test lead terminals COM/+.
Application notes:
The DC

A function is designed especially for HVAC/R flame sensor applications. The
0.1

A resolution is useful for identifying the minute current changes in flame detector
applications. Flame signal current check should indicate steady flame signal of at least
2

A for a rectification type, or 1.5

A for an ultraviolet type (8

A for self checking
systems). If a flame signal current with inadequate strength or fluctuation beyond 10%,
check the following to avoid the risk of unwanted flame relay dropout :
For gas or oil flames (Minipeeper):

Low supply voltage

Detector location
 Defective detector wiring

Dirty viewing windows

Faulty Minipeeper
For oil flames (Photocell):

Detector location & wiring
 Smoky flame or poorly adjusted air shutter

Faulty Photocell

Temperature over 165
o
F (74
o
C) at photocell
For gas flames (Flame Rod):

Ignition interference (A flame signal current difference with the ignition both on and
off greater than 0.5
 A indicates the presence of ignition interference)

Insufficient ground (must be at least 4 times the detector area)

Flame lifting off burner head (ground), or not continuously in contact with the flame
rod

Temperature in excess of 600
o
F (316
o
C) at the flame electrode insulator causing
short to ground.