Kikusui PLZ-3WH Series, Operation Manual

Page: 91 / 172

4-51
Chapter 4: Operating Procedure
4.6.2 External Control of CR (Constant Resistance) Mode
(a) External voltage method
An external voltage from 0 to approx. 10 V is applied to the load unit to change the resistance in proportion to the
voltage.
7
8
COM
＋
Approx.10k
Ω
Equivalent circuit
J2
＋
−
Ein
Ro ≒ R SET value
Rmin × 10
Ein
： External voltage
0
＜
Ein
≦
10(V)
：
Working resistance
：
Minimum resistance of CR mode
：
Set resistance of CR mode
：
Input current
：
Rated voltage
Io ＝ ≒ ＋
Eo Ein
Rmin × 10
Eo
Ro
Eo
R SET value
Ein
Ro
Rmin
R SET value
Io
Eo
Fig. 4.6-5
● ● ● ● ● Setup procedure
(1) Press the [POWER] switch to turn off the load unit.
(2) Connect the external voltage to J2 terminals 7 and 8 on the rear panel.
(3) On the rear panel, set the external control setup switch [SW2] to the “REM” position and [SW3] to the “V” position.
(4) Press the [POWER] switch to turn on the load unit.
(5) Press the [R SET] key on the front panel to enable the CR mode.
(6) Set the external voltage to 0 V, and adjust the maximum resistance with the semifixed resistor [OFS] on the rear
panel. Then, set the external voltage to 10 V, and adjust the minimum resistance with the semifixed resistor [FS]
on the rear panel.
(7) Using the [SHIFT] + [STOP] (KEYLOCK) keys, put the load unit into keylock condition.
CAUTION
• Up to
±
11 V can be applied between J2 terminals 7 and 8. If the voltage exceeds this value,
the load unit may be damaged. Unit accuracy cannot be guaranteed when the voltage is at
0 V or below or at 10 V or over.
• The J2 terminal 8 is connected to the negative side of the load terminal inside the load unit.
Take care so that this terminal 8 will not contact any of the other terminals.
When the external voltage is used for external control, the working resistance is a sum of the resistance proportional to
the external voltage and the RSET value set on the load unit panel. However, only the RSET value appears on the
display, meaning that the working resistance is not equal to the RSET value. Therefore, to prevent changing the RSET
value mistakenly, put the load unit into keylock condition.
To prevent noise interference, use twisted pair or shielded signal cable. Also, use stable external voltage to generate
less noise.
When the external voltage is used for external control, even the CR mode needs the same terminals as the CC mode.
Therefore, always recheck the operating mode.