Scope of application
The JT18 series DC electromagnetic universal relay (hereinafter referred to as the relay) serves as a time (power-off delay), voltage (intermediate), and undercurrent relay, mainly used as a control relay for main circuits with DC voltage up to 440 volts, DC voltage up to 220 volts, and DC current up to 630 amps.  

Model and its meaning



Voltage relay model JT18- □
Time relay model JT18- □/1 (with a delay of 1 second)
Model JT18- □/3 (with a delay of 3 seconds)
JT18-□ / 5
Undercurrent relay model JT18- □ L

Type and classification
1. Relays are classified as open type.
2. Relays (voltage, time) are divided into five types according to the rated working voltage of the coil: 24, 48, 110, 220, and 440 volts.
3. Relays (under current) are divided into fourteen types based on the rated working current of the coil: 1.5, 2.5, 4, 6, 10, 16, 25, 40, 63, 100, 160, 250, 400, 630 amps.
4. Relays are divided into three types according to their purposes: voltage relays, time relays, and undercurrent relays.
5. Relays are divided into two types of contacts: one contact element (1 normally open, 1 normally closed) and two contact elements (2 normally open, 2 normally closed).
6. According to the wiring method, it can be divided into two types: front board wiring and back board wiring.
7. According to the installation method, it can be divided into two types: two hole installation and three hole installation.

Main technical parameters of JT18 series DC electromagnetic universal relay

（1） The rated heating current of relay contacts is 10 amperes.
（2） The working system of relays mainly includes an eight hour working system and a repeated short-term working system. The rated operating frequency of the repetitive short-term working system is 1200 times/hour, and the rated power on duration is 40%.
（3） The operational performance of voltage relays. When in cold state, the attraction voltage of the coil should be adjustable within the range of 30% to 50% of the rated working voltage, or the release voltage should be adjustable within the range of 7% to 20% of the rated working voltage, and the return coefficient is not specified. A relay with two contact elements allows the suction voltage to be adjusted within the range of 35-50% of the rated operating voltage. Factory set according to the minimum suction voltage value.
（4） The operational performance of time relays. There are two methods to obtain delay for time relays:
(1) Short circuit the coil (at this time, a resistor should be connected in series with the power supply to prevent power short circuit).  
(2) Disconnect the coil. When the coil of the relay is subjected to a rated working voltage of not less than 75%, the delay range obtained by the above two methods complies with the provisions of the table.

JT18 series DC electromagnetic universal relay appearance and installation dimensions

Ordering Notice
When placing an order, it is necessary to specify the name, model, rated voltage (current), contact specifications, wiring before or after the board, installation form, and order quantity of the relay.
Example: 1. If you need to order 5 relays with a 3-second delay, 2 normally open and 2 normally closed contacts, and a coil voltage of 110 volts, and a regular type (two hole) base plate installation, you should fill in the order in the following format: Time Relay JT18-22/3 110V 5 units
2. If you need to order 8 undercurrent relays with 100 amperes, normally open and normally closed contacts, rear wiring, and special type (three hole) installation on the base plate. The order should be filled out in the following format:
Undercurrent relay JT18-11L100 A, board mounted, special type installation base plate 8 units.