SZJ300A Normally Open DC Contactor

The working principle of a normally open DC contactor is derived from its electromagnetic coil. When the coil is energized, it generates a magnetic field that attracts the moving contact to the stationary contact, effectively closing the circuit. This action allows current to flow through the circuit, enabling the connected equipment to operate. Conversely, when the coil is de-energized, the magnetic field dissipates and the contacts return to their normally open state, interrupting the flow of current. This basic operation makes the normally open DC contactor an important tool for controlling circuits.

product details

FEATURES

A defining characteristic of a normally open DC contactor is its design. In the default state, the contacts remain open, blocking the flow of current. This design ensures that power is supplied to the circuit only when the contactor is energized. This feature is particularly useful in applications where safety and energy efficiency are critical, as it minimizes the risk of accidental circuit closure and energy waste. The normally open configuration is ideal for applications that require the device to remain closed until explicitly activated.

SAYOON MODEL IMPLICATION

SZJ	300A	-S	-□	-□	/□
1	2	3	4	5	6

1	Product type
2	Rated current
3	Auxiliary switch: None-Without auxiliary switch; S-With auxiliary switch
4	Mounting bracket type: None-M Horizontal (default); E-Level embedded; X-Oblique; L(N)-Vertical; E1-Level embedded single direction
5	Other function codes
6	Coil rated voltage: 12V, 24V, 36V, 48V, 60V, 72V etc.

Uses

This product have one normally open contact, for electric vehicles, telecommunication equipment, engineering machinery, car batteries, electric forklift trucks, trains, ships, electronic control systems such as uninterruptible power supply.

Technical Parameters: (Version 2.44)

SAYOON Product Type	SZJ300A
Contact form	1 NO
Coil Rated voltage (DC V)	6V,12V,24V,36V,48V,60V,72V,84V,120V,150V etc.
Contact voltage (DC V)	≤60V
Rated load current of contact 48V circuit (DC-1)	300A
Typical voltage drop across contacts per 100A	≯80mV
The cooling pull-in voltage at (20±5)℃ (V)	≯70%
The cooling drop-out voltage at (20±5)℃ (V)	≯40%,≮5%
Working voltage range of 40℃ coil	0.8-1.2Us
Drop-out time (n/o contacts to open)	15ms
Pull-in time (n/o contacts to close)	10ms
Maximum bounce time for contact connection	10ms
Maximum bounce time for contact disconnection	3ms
Insulation resistance	20MΩ
Electric strength to resist	50Hz/60Hz 1000VAC 1minute
Typical fault currents which can be ruptured	1000A/5ms at 48V/DC
Coil power (W)	Start: 120-170, Keep: 4-10
Temperature rise of coil (K)	≤40
Temperature rise on outgoing terminal (K)	≤65
Electrical life	20,000 times
Mechanical life	300,000 times
Work specification	Continuous
Contact material	Ag alloy
Load terminal type	M8 Screw
Coil terminal type	M4 Screw
Auxiliary contact rated load (optional)	2A/48VDC, 5A/24VDC
Testing organization certification	CCC,CE,FCC,RoHS

Note:As regarding to the different using environments of customers which requires different focus of the functions,and in order to improve the comprehensive properties of our products,sayoon may adjust the coil parameters,temperature rise and so on. The above parameters are for reference only, For details, please refer to the guidelines for selection and use of the SAYOON DC contactor.

Load Characteristic Curve

Installation Diagram

Wiring Diagram

Temperature Curve

Mechanical Ability And Use Of The Environment

Contact lead M8 tightening torque (N.m)	≯9.0 appropriate
Coil lead M4 tightening torque (N.m)	≯1.2 appropriate
Ambient temperature	-25~+70℃
Relative humidity	+20℃ 98%
Vibration freq. atthe fixed position	3G, 1～50Hz amplitude 0.5mm
Concussion	(60～100) time/minute、acceleration≤4g
Altitude	2000m
Installation direction	Random
International protection	IP40 (According IEC60947)

Order Instruction

SAYOON Product Type	SZJ300A
U.N.W.	450g
U.G.W.	480g
Package QTY.	50PCS
Mounting bracket type	None - M Horizontal (default), E Level Embedded, X Oblique, L (N) Vertical, E1 Level embedded single direction

When ordering, please state the following: name, full model, control coil voltage specification, installation frame type, whether with auxiliary contact, order quantity. For example: DC Contactor SZJ300A/24V 100pcs, indicating the load rated current 300A, without auxiliary contact, default mounting bracket, coil control voltage 24V purchase 100pcs. Special voltage specification products, such as user needs can be special order.