Hitachi NJI-350B manual 10-7, Life characteristics 125 V AC

Chapter 10 PLC Installation, Mounting, Wiring

(a)Wiring to the relay output terminals 1] Life of relay contacts

Life curve of relay contacts

Figure 1 Life characteristics (125 V AC)

	1000
	500
times)	100			AC 125 V cos φ =1
(10,000	50				AC 125 V cos φ =0.7
	20
life
	10
Switching		AC 125 V cos φ =0.4
	1	1	2	3	4	5	6
	0
				Contact switching current (A)

Figure 2 Life characteristics (250 V AC)

	1000
	500
times)	100			AC 250 V cos φ =1
(10,000	50				AC 250 V cos φ =0.7
	20
life
	10
Switching
		AC 250 V cos φ =0.4
	1	1	2	3	4	5	6
	0
				Contact switching current (A)

Figure 3 Life characteristics

1000
	500
times)	100			DC 30 V L/R=1 ms
(10,000	50				DV 30 V L/R=7 ms
	20
life
	10
Switching
		DC 30 V L/R=15 ms
	1
		1	2	3	4	5	6
	0
				Contact switching current (A)

Life of the contact is almost in squared reverse proportion to the current, so be aware that interrupting rush current or directly driving the condenser load will drastically reduce the life of the relay.

When switching is made with high frequency, use a transistor output module.

2] Surge killer

For inductive load, connect a surge killer (condenser 0.1 ∝F, + resistance of approx. 100 Ω) in parallel to the load. Also, for DC load, connect a flywheel diode.

3] Fuse

A built-in fuse is not used in this module. Install a 6 A fuse in the common to prevent the external wiring from burning out.

For the independent contact output section, install a 2A fuse per circuit.

(b)Wiring to the transistor output terminals 4] Flywheel diode

For inductive load, connect a flywheel diode in parallel.

5] V and C terminals

Always connect a V terminal and C (common) terminal. If the module is used without connecting these terminals, the internal flywheel diode may not function and the module may malfunction or break down.

6] Fuse

There is no built-in fuse to prevent external wiring burning. Therefore, it is recommended that a fuse be installed externally to prevent the external wiring from burning out. (This does not protect the internal transistor elements.) If the external load is short-circuited, please contact us for repair.

10-7