H-25C Instruction Manual
Instruction 3015-0216
34
(3)
Wiring the Alarm Contact Output Terminals (if equipped with contact
output function)
(3) If you wish, you can order the H-25C with a function that outputs a contact signal when the measured
value exceeds the alarm point. If your instrument has this function, connect the wiring from the
instrument to signal destination. (See Figure 4.1.)
Note: See Subsection 2.2.4 regarding the state of the contacts when the alarm contact signal is
output.
The maximum allowable voltage across the contacts is 220 V DC or 250 V AC. The maximum
allowable current is 2 A. Note that if electrical noise is present at the connected load (or generated
by the switching action), you should connect a noise killer, or surge suppression network, across the
terminals, or take other appropriate countermeasures, since such noise may cause improper
operation.
(4) Turn the Power Switch to the ON position to place the H-25C in operation. Insert the key provided
into the keyhole in the power switch, and turn clockwise (to the right). Connect the probe before
doing turning on power, if it is not already connected.
The H-25C will go into measurement mode after about 180 seconds of warm-up. During the warm-
up time or immediately after transferred to the measurement mode, check the following.
•
Make Sure that the Fan is Running
The fan serves two purposes. One is to bring cooling air into the instrument. The other, if the
instrument has the auto calibration option, is to maintain a consistent atmosphere inside the
instrument. Thus it is vital that the fan be turning properly.
Note: Calibration gas is normally flowing out not only from the ' CAL PORT " probe insertion
opening, but also from the air intake hole (on the inside of the 'CAL PORT" section) as wen. In
auto calibration the probe inserted in the " CAL PORT " takes in air from inside the instrument
through this hole, together with the calibration gas. If the fan steps, calibration gas will
accumulate in the air inside the instrument, and its effects will make accurate calibration
impossible.
•
Check the Cal Gas Secondary Pressure Displayed during Warm-up. (If auto calibration option is
installed.)
The calibration gas secondary pressure is normal if the indication is in the 100 to 200% range.
Auto calibration can be performed if this indication is normal or, even if abnormal, is not less than
50% (although the " CAL FAIL " indicator will be flashing when in measurement mode). If it is
below 50%, auto calibration is not possible.
